Would it be necessary for me to renounce said affiliation prior to registration with the Church of Satan?
It speaks very well of you that you have outlined what you see as your dilemma so clearly, as well as providing useful (and also clear) background context for your relationship, past present and future, with Satanism.
To the best of my understanding, the answer to your question is no, absolutely not, it is not necessary to renounce membership in that particular organization to proceed with CoS affiliation.
The two general guidelines for seeing a conflict in affiliations are, one, does the other organization explicitly avow an adversarial relationship with the Church of Satan
, or explicitly work towards goals in direct and unambiguous conflict with CoS goals, and two, does the organization explicitly condone, allow, or encourage any type of criminal activity.
In this case, the answer is pretty clearly no.
You are good to go.