I had the same sort of question a few months ago, If I should send a letter, because I felt out of principal I should cut the cord, but I simply don't care anymore, and the fact that half my extended family are Jws it would make it very difficult at family functions for those ones. so for them i guess i play along. when all of those older ones are dead, lol, and im like 60, maybe Ill have peace of mind.
Its odd, once you stop going to meetings your treated as if you have done something wrong and avoid you anyway. when and If I bump into someone out at a market or someplace public they are forced to say hello, and smile but then quickly move on. These people have no clue what s going on, but , I must be evil,lol.
Wicca is a following that does not have a lot of ' pomp and circumstance' and 'preaching', so that they would need to know what your doing. id sooner just , be way too busy, fill the schedule, and when with family make sure you are doing something that blocks the way for them to open up and questions of discussion. the thing is I have my mind and my own opinion and they cannot take that from me anymore. that alone is my closure.