a couple times I've changed my mind and tried to delete a map
but when I do it crashes the editor and I have to relaunch the whole game again

any ideas what im doing wrong?

It's a bug that should be fixed once the server is done patching

I have found that if I delete any storyline parts under the "story" tab that link to that map, then the map itself can then be safely deleted.

This should have been fixed with Thursday's patch.