Unity Serializer Overwrite savegame

hi there! i'm working on a save menu with unity serializer, but i need a help! i want to overwrite a gamesave with click on SaveGame if there is 1 save, but for now i have done only a button for delete savegame, there is the code, i want the possibility to overwrite the unique savegame by clicking on Save Game button!

     if(GUI.Button(Rect(800,310,430,70), "Save Game"))
     {
         LevelSerializer.MaxGames = 1;
            LevelSerializer.SaveGame(gameName);
      }
 
          for(var sg in LevelSerializer.SavedGames[LevelSerializer.PlayerName]) { 
         if(GUI.Button(Rect(800,410,430,70), sg.Caption)) { 
          LevelSerializer.LoadNow(sg.Data);
          } 
     } 
     
             for(var sg in LevelSerializer.SavedGames[LevelSerializer.PlayerName]){
             if(GUI.Button(Rect(800,510,430,70), "Delete: " + sg.Caption)){
             sg.Delete();
         }
     }