Cant delete matched songs, frustrated.

I can not delete songs that I've matched with iTunes. I matched a few old CDs with hastily written metadata which is half wrong. Now no matter what I do they keep reappearing everytime I update match or turn it off and on again. These songs wont keep/update any new metadata I assign them nor will any changes sync with iPhone. I can keep adding new music fine but these songs just wont go. Is this how its supposed to be? Im afraid to match any more songs, I must be really careful how my music gets matched because thats how its going to stay, forever with no option to delete it. Crazy.