I assume that, prior to asking this question, you reviewed your Bylaws to determine that you currently do not have a cap on the number of renters that your Association allows for. If so, then you will need to have a vote.
First, the Board will have to form a quorum (majority ruling) in favor of such an amendment. Once it has passed throught the Board and depending on what your Decs and Bylaws state, you may be able to do one of two things:
Pass the amendment and wait 30-60-90 days (depending on your Bylaws) for the Association as a whole to come up with 66 2/3% of the owners to petition against it or pass the amendment and secure 66 2/3% vote in favor of it.
Without seeing your actual Bylaws it's hard to state what yours allows for. However, the former is most common.
Once you have completed all of this, you will then begin the filing for an amendment. My advice to you is to hire a Real Estate attorney to help you with this process as it is often confusing and time consuming. You will have to get a quorum of the Board in order to hire an attorney, as well.
My recommendation is to have a solid meeting of the minds to determine at this point if you have any other changes that need to be made to the Bylaws, as you might as well get it all over with in one shot.
Bear in mind, however, that, if you amend the Bylaws to reflect no renters or a certain amount of renters, that those who are already renting are more than likely "grandfathered" in until the end of their current lease.
Hope this helps.