Is there a way? Thanks.

Check the item(s) you want to remove, click "With Selected: Remove from set" and click submit.

What about deleting the sets altogether?

There is no way to delete a set. Just simply send it to any user. Universalset is the account specifically for empty sets if I recall.

You could also put it on market, but there is no way to delete it

the question has been answered so im going to close this