Instead of burning your bridges and terminating your account why don't you exercise the options listed in the Your Choice section of the Alz. Conn. Terms and Conditions agreement? I posted them below.

Your choice
We respect your privacy and recognize that you may wish to limit the ways in which we contact you. Simply send an email to info@alz.org with the following information:
• To remove your name from mailing lists shared with other organizations, please provide your full name, mailing address and a sentence requesting removal.
• To remove your name from the Alzheimer's Association postal mailing list, please provide your full name, mailing address and a sentence requesting suppression of your personal information in our files.
• To review or correct your personal information with the Alzheimer's Association, please provide your name and a sentence requesting a review or a correction.