You can cancel your ADOIT:Community membership and hence delete your ADOIT:CE account here.
You’ll receive an email to confirm the deletion of your account. After successful confirmation, the deletion of your account will be processed immediately.

If you just do not want to use your ADOIT:CE software account any longer, but would still like to stay a member of the ADOIT:Community, just let time do the work for you. Your ADOIT:CE account will expire automatically after 60 days of inactivity.