Taken 10mg prednisone for 45 days for RA. How fast to taper off 1 mg per week or 1 mg every 2 weeks?

Impossible to say. Are you seeing a rheumatologist? Are you on any other meds for your RA? Do you still have joint pain?
You need to see a rheumatologist if you are not currently seeing one. Prednisone should not be used as the only therapy for RA. There is no single best way to taper prednisone without knowing more specifics.