Ohhh. I read:
... remove a player from the tables tab?
... and my brain concluded you just wanted a player to not show up on the Tables tab, as if you just didn't want a particular player to be included in the seating. You want to be able to remove a player from the tournament directly from the Tables tab, not just be able to undo a player's buy-in directly from the Tables tab. I see now.

Yeah, should be pretty easy to add.