diff --git a/database/migrations/structure/20210510_2000_challenge.sql b/database/migrations/structure/20210510_2000_challenge.sql
index 0b9a657..810d849 100644
--- a/database/migrations/structure/20210510_2000_challenge.sql
+++ b/database/migrations/structure/20210510_2000_challenge.sql
@@ -48,6 +48,6 @@ CREATE TABLE `guesses` (
   PRIMARY KEY (`id`),
   KEY `user_id` (`user_id`),
   KEY `place_in_challenge_id` (`place_in_challenge_id`),
-  CONSTRAINT `guesses_user_id` FOREIGN KEY (`user_id`) REFERENCES `places` (`id`),
+  CONSTRAINT `guesses_user_id` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`),
   CONSTRAINT `guesses_place_in_challenge_id` FOREIGN KEY (`place_in_challenge_id`) REFERENCES `place_in_challenge` (`id`)
 ) ENGINE = InnoDB DEFAULT CHARSET = utf8mb4;
\ No newline at end of file
diff --git a/src/Controller/GameFlowController.php b/src/Controller/GameFlowController.php
index 2e33820..71ea558 100644
--- a/src/Controller/GameFlowController.php
+++ b/src/Controller/GameFlowController.php
@@ -151,7 +151,7 @@ class GameFlowController
         
         if (!isset($currentPlace) || $withHistory) {
             $withRelations = [User::class, PlaceInChallenge::class, Place::class];
-            foreach ($this->guessRepository->getAllInChallenge($challenge, $withRelations) as $guess) {
+            foreach ($this->guessRepository->getAllInChallenge($challenge, $withRelations) as $guess) { 
                 $round = $guess->getPlaceInChallenge()->getRound();
     
                 if ($guess->getUser()->getId() === $userId) {
diff --git a/src/Controller/UserController.php b/src/Controller/UserController.php
index 36397d8..2860d97 100644
--- a/src/Controller/UserController.php
+++ b/src/Controller/UserController.php
@@ -9,7 +9,10 @@ use MapGuesser\Interfaces\Response\IRedirect;
 use MapGuesser\OAuth\GoogleOAuth;
 use MapGuesser\PersistentData\PersistentDataManager;
 use MapGuesser\PersistentData\Model\User;
+use MapGuesser\PersistentData\Model\UserInChallenge;
+use MapGuesser\Repository\GuessRepository;
 use MapGuesser\Repository\UserConfirmationRepository;
+use MapGuesser\Repository\UserInChallengeRepository;
 use MapGuesser\Repository\UserPasswordResetterRepository;
 use MapGuesser\Repository\UserPlayedPlaceRepository;
 use MapGuesser\Response\HtmlContent;
@@ -29,6 +32,10 @@ class UserController implements ISecured
 
     private UserPlayedPlaceRepository $userPlayedPlaceRepository;
 
+    private UserInChallengeRepository $userInChallengeRepository;
+
+    private GuessRepository $guessRepository;
+
     public function __construct(IRequest $request)
     {
         $this->request = $request;
@@ -36,6 +43,8 @@ class UserController implements ISecured
         $this->userConfirmationRepository = new UserConfirmationRepository();
         $this->userPasswordResetterRepository = new UserPasswordResetterRepository();
         $this->userPlayedPlaceRepository = new UserPlayedPlaceRepository();
+        $this->userInChallengeRepository = new UserInChallengeRepository();
+        $this->guessRepository = new GuessRepository();
     }
 
     public function authorize(): bool
@@ -209,6 +218,14 @@ class UserController implements ISecured
             $this->pdm->deleteFromDb($userPlayedPlace);
         }
 
+        foreach ($this->userInChallengeRepository->getAllByUser($user) as $userInChallenge) {
+            $this->pdm->deleteFromDb($userInChallenge);
+        }
+
+        foreach ($this->guessRepository->getAllByUser($user) as $guess) {
+            $this->pdm->deleteFromDb($guess);
+        }
+
         $this->pdm->deleteFromDb($user);
 
         \Container::$dbConnection->commit();
diff --git a/src/PersistentData/PersistentDataManager.php b/src/PersistentData/PersistentDataManager.php
index 273eefc..b0274e4 100644
--- a/src/PersistentData/PersistentDataManager.php
+++ b/src/PersistentData/PersistentDataManager.php
@@ -60,7 +60,7 @@ class PersistentDataManager
             if (strpos($key, '__') == false) {
                 $method = 'set' . str_replace('_', '', ucwords($key, '_'));
 
-                if (method_exists($model, $method)) {
+                if (method_exists($model, $method) && isset($value)) {
                     $model->$method($value);
                 }
 
@@ -70,7 +70,7 @@ class PersistentDataManager
 
                 $method = 'set' . str_replace('_', '', ucwords($key, '_'));
 
-                if (method_exists($model, $method)) {
+                if (method_exists($model, $method) && isset($value)) {
                     $model->$method($value);
                 }
 
diff --git a/src/Repository/GuessRepository.php b/src/Repository/GuessRepository.php
index 7c9b4df..eeca0a0 100644
--- a/src/Repository/GuessRepository.php
+++ b/src/Repository/GuessRepository.php
@@ -19,7 +19,15 @@ class GuessRepository
         $this->pdm = new PersistentDataManager();
     }
 
-    public function getAllByUserAndChallenge(User $user, Challenge $challenge) : Generator
+    public function getAllByUser(User $user): Generator
+    {
+        $select = new Select(\Container::$dbConnection);
+        $select->where('user_id', '=', $user->getId());
+
+        yield from $this->pdm->selectMultipleFromDb($select, Guess::class);
+    }
+
+    public function getAllByUserAndChallenge(User $user, Challenge $challenge): Generator
     {
         $select = new Select(\Container::$dbConnection);
         $select->innerJoin('place_in_challenge', ['place_in_challenge', 'id'], '=', ['guesses', 'place_in_challenge_id']);
@@ -29,7 +37,7 @@ class GuessRepository
         yield from $this->pdm->selectMultipleFromDb($select, Guess::class);
     }
 
-    public function getByUserAndPlaceInChallenge(User $user, Challenge $challenge, Place $place) : ?Guess
+    public function getByUserAndPlaceInChallenge(User $user, Challenge $challenge, Place $place): ?Guess
     {
         $select = new Select(\Container::$dbConnection);
         $select->innerJoin('place_in_challenge', ['place_in_challenge', 'id'], '=', ['guesses', 'place_in_challenge_id']);
@@ -57,7 +65,7 @@ class GuessRepository
             $necessaryRelations = [PlaceInChallenge::class];
             $withRelations = array_unique(array_merge($withRelations, $necessaryRelations));
         }
-        
+
         $select = new Select(\Container::$dbConnection);
         $select->where('challenge_id', '=', $challenge->getId());
         $select->orderBy('round');