Hi,
I have never had a Bessa I in my hands but it should be:
Set lens to infinity.
Unscrew (not completely) three small screws holding the front element.
Take out the front ring carefully without any rotation movement.
Mark the place the front element is set (marker, thing scratch, etc)
Unscrew the front element.
If you want to take out the middle element probably a rubber friction tool will help.
Careful with the grease between this thread, probably you will need to clean it out and lube it again later for a smooth focusing.
Without a photo of your camera, this is how I would do it as my previous experience. I hope it helps.
Regards,
Alex