You can't get rid of your progens, but you can release other wolves. Somewhere near the name of the wolf there's a little pine tree thing. If you click(or tap) that it'll come up with a box that asks you if you really want to release that wolf. Once you click 'yes' then it'll process that for a moment and then the wolf is g o n e
If you are at the point where you're looking to profit more off of your releases, using the toad companions from the mole market you can passively level dogs you want to release to level 10; that way you can also start leveling them before they are adults. Releasing at level 1 gives 1000 pebbles, releasing at 10 gives you 10,000 pebbles and a knucklebone token that you can sell for more profit or save up and use to hunt for WWs if that is your thing.