Serious music help??

[MandarinRose26]

So, I have the Razr M. I set it so when I plug my phone into my computer, it will automatically open up Windows Media Player since I usually just plug my phone into my computer to sync music. Well today I did it to charge it... and the dumb phone synced EVERYTHING. All of my pics I had saved to my comp, my music, my videos, everything. I got the pics and videos off of my phone, but I can't delete the music! Yes, I can go 1 by 1, but is there a way just to delete all of it at one time? I took my SD card out so all of the music I want is on there.

How do I delete all of the music on my phone at one time? Thanks!