We're sorry to see you go and we'd like to help however we can. We have a Community Help and Support section with numerous FAQ's that you find helpful. Here are a few in particular:
If you still wish to cancel your Insiders account, we will honor your request. Deactivating your Insiders profile has no impact whatsoever on your Marriott Rewards account or status. Simply send a direct message to communitymanagers and explain why you would like to disable your profile.