I wanna delete one of my songs but I don't know how to do it.

there's a drop down menu next to your song title on your music page... http://my.bandamp.com/music.html
you can select "delete mp3" there provided the song hasn't been in a battle before...

so songs that have in a battle before cannot be deleted???

The idea is that when they have been in a battle and received a ranking then they cannot be deleted. This will eventually change, since the site has no rights to hold any intellectual property hostage - the artists themselves should remain in full control over their work, regarding having it publically available, after they upload it here (read the Terms). But for now the system doesn't work that way. Unfortunately it appears that if a song has been in a battle and did not receive a ranking it cannot be deleted or put into another battle either. Seems like a flaw in the code, because this IS intended to be possible.

Anyway for any other questions I will ask you to read the FAQ first before asking questions, because that's where you'll find most of the info for this site. And perhaps read some bits of the Ideas&Feedback forum and other questions posted in Tech Support.

regards,
PX (just a mod)