Two Buttons

burn the furry then toss it in the ocean after it stops burning so it isn't ever seen again

Both

Drowning it would be incredibly difficult as fursuits generally hold a lot of air.

Burn because it hurts much more(a small taste of hell) and then drop them into the ocean, and let the sharks eat it.

I would soak the furry in oil then set it on fire then put its feet in concrete and send it to the bottom of the ocean

Nothing. If i HAD to kill one id just shoot them