O'Reilly automotive will loan you a wheel bearing press. The big kit was $450 deposit, but it is fully refunded upon returning. Then you need to find something with the right diameter to press out the metal ring. Hopefully one of the rings in the kit will work. The kit has a C clamp to press out the ring, it is made to press out bearings but should work for this too.
Option B would be to use a hacksaw and cut the ring, but you might accidentally cut the aluminum swing arm if you aren't careful.
Other auto stores also have bearing kits, but O'Reilly had the biggest selection of rings that I found.