How to cut off sections of a map

b0mbtrack

I made a map and I want to cut some of it out and zoom in on one area to make a close up map of that specific area. I know how to do the scaling but I don't know how to cut off sections of an already made map. Is there a way to do this? Thanks

b0mbtrack

Nevermind, I just outlined with a land mass what I wanted and removed the old one from underneath.