https://www.ebay.ca/myb/SavedSellers
Wow, talk about poor computer design -- I don't see any obvious way to delete.
However, if you unheart it -- it says "Saved seller removed" at the bottom of the screen -- except seller is still showing (perhaps the Seller gets removed after a refresh?)
tyler@ebay -- something for the eBay improvement shop (deletion should be added to the drop down menu)