Actually there are no artist accounts, if there were any. If you meant artist site, like this - you can't delete it. But if you want to update biography of your band/music, you can do it as normal user and edit biography on yours' artist page. I suggest you to write additional info rather than deleting everything: it's more useful and don't destroy the work other people did on it (biography, as well as artist site, is meant to be more "archive of music" than source of harmful info) The choice is yours, anyway
For the next time, I recommend looking at FAQ here, this question is asked really frequently. But since I know how hard is to find FAQ, I wrote you short answer.