To expunge a deleted claim click on the three dots that appear at the top-right-hand of a claim when you hover over it, or right-click on the claim to open the claim menu bar.
Select ‘expunge’.
Note that expunging a deleted claim removes all record of it from a discussion. If you later need that claim, or a claim beneath it, it will not be there.
For information on how to delete a claim see Deleting a Claim.