Add ability to uninstall an extension

src/Core/Settings/DatabaseSettingsRepository.php

@@ -35,4 +35,9 @@ class DatabaseSettingsRepository implements SettingsRepository
 
         $query->$method(compact('key', 'value'));
     }
+
+    public function delete($key)
+    {
+        $this->database->table('config')->where('key', $key)->delete();
+    }
 }

src/Core/Settings/MemoryCacheSettingsRepository.php

@@ -42,4 +42,11 @@ class MemoryCacheSettingsRepository implements SettingsRepository
 
         $this->inner->set($key, $value);
     }
+
+    public function delete($key)
+    {
+        unset($this->cache[$key]);
+
+        $this->inner->delete($key);
+    }
 }

src/Core/Settings/SettingsRepository.php

@@ -9,4 +9,6 @@ interface SettingsRepository
     public function get($key, $default = null);
 
     public function set($key, $value);
+
+    public function delete($key);
 }