Ive had a lot of trouble with bad DVDs so ive been adding and deleting like hell the last few days. However, now I cant seem to be able to remove entries from mylist anymore. I am using the webinterface here at anidb.net.
Wait a couple of days to make sure a maintenance update has taken place. That's usually all that it takes. I've had twice in the past as well. If it's still not removed after a couple of days, post here again.