Congratulations! You have succeeded in removing the focus calibration ring.
Now, to put it back correctly, you'll need to do a quick focus calibration. Put the ring back on, put on the elements, and find a good target. Focus on the target using the ground glass, and check the focus on the film plane to see if it too is in focus. To check focus on the film plane, I grab a ground glass, and secure it (aka tape it) at to the rails for the film. Fun times.
If it isn't in focus, flip the ring vertically, and try again.
You have a 50/50 chance of getting it right the first time.