Can't delete favorites in Phone app

I can't delete any listed Favorites in the Phone app; please help. When I go into the Phone app and tap on Favorites (lower left corner), it lists all my favorite contacts. I can start the deletion process by either tapping "Edit" on the top left, then clicking the red minus sign next to any contact, or by swiping to the left on any contact. In either case, I get a red "Delete" icon on the right of the contact. So far so good.

However, when I try to tap that "Delete" icon, nothing happens. Also, I can't find any other way to delete favorites, e.g., through the Contacts app or on my iMac (with which the iPhone is synced).

Please help!