Guys, thank you all!
Today I made some tests. I used our kitchen oven. First, I set it to 200 ⁰C and put the assembly in it for about 5-7 minutes. I tried to separate the ring and bearing, but I didn't manage to. I then tried 300 ⁰C, but that didn't help too, maybe I didn't wait enough. Finally, on the third approach at 350 ⁰C (the maximum temperature of the oven) and some more time in it, I could hammer gently the ring out, using the round wooden blocks. It seems the bearing and ring were glued together.
I have another concern, though. On the pictures you could see the ring changed it's color to much darker. Maybe an oxide built up. Do you have any recommendations on how to clean it or I should buy a new one? I'm thinking about some alcohol and maybe acetone to clean the glue residue. Afterwards, if the new bearing doesn't fit, I'd have to heat the ring again and try again, but I'd like to get it cleaner first.

Thank you!
Nickolay