Remove a truck wreck from game

Hi! We're trying to build a safe zone in the Airfield (krasno) and there is a truck wreck that we want to remove, it's on position "11880 12451".

I managed to find it in the mapgrouppos.xml file, so I removed it then restarted the server, but I can still see it in the game.

Is it possible to remove it, Am I doing something wrong? Thanks.