You can cancel your membership of the ADONIS:Community and hence delete your ADONIS:CE account here.
You will receive an email to confirm 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 ADONIS:CE software account any longer, but would still like to stay a member of the ADONIS:Community, just let time work for you. Your ADONIS:CE account will expire automatically after 60 days of inactivity.