iTunes/my music question

I am trying to free up some space on my hard drive and have this question:

I have lots of music in the "my music" folder and the same music is in my iTunes.
Should I delete what's in my music. Will that affect my iTunes? It just seems like it would be
Taking up double the space.

Does anyone know?

I don't think it will but just in case only delete one song but if something happens like it did with me I was forced to renown load every song I had