I see nothing in the NT scriptures speaking of church "membership" or "church" roles in the sense that we speak of it today. Our membership rules are a modern invention. What I see in the writings of Paul is that all were "members" of Christ's church, but gathered in local assemblies to worship, which we call the local church. Once a part of the local assembly they were subject to the rules of church discipline as outlined by the Lord Himself. There is no evidence that a person required permission to leave the local assembly or even the body of Christ. If they chose to leave the church and go back into the world, they were not true believers, as John has said:
1Jo 2:19 They went out from us, but they were not of us; for if they had been of us, they would [no doubt] have continued with us: but [they went out], that they might be made manifest that they were not all of us.
I am NOT defending the woman in this story.