Holds that don't disappear from your expired holds list are the result of items on the hold shelf which have expired and then were checked out before being checked in. To prevent this from happening in the future, if an item on the hold shelf has expired, CHECK IT IN BEFORE YOU CHECK IT OUT to anyone.
For those items that keep showing up on the expired holds list, but are not on the shelf - check the item in DAMAGED, then put it in TRACE status. This will keep your expired holds list current.