Q: How to I reset (empty) my iCloud account without deleting music on my pc?

I have 50 gigs of music to erase in iCloud, but I don't want to erase anything on my hard drive.  It sounds simple enough, but I'm having a problem doing this.  I'm afraid I'll erase everything on my hard drive as well, and I don't want that.  I only want to erase the music in iCloud.