how do i delete maps from the mainmenu.map

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i just wanted to know if i can delete maps that i dont want from the mainmenu.map in dot halo. I tried doing this when i got the allied map pack and when i tried to delete the 4 new maps (turf, sanc, warlock, and containment) i still got the picture for those ones. I also tried replacing those maps with new ones, but all it does is failed to load map. thanks if anyone can help me