Add User to Campaign

I am trying to add a user to Campaigns, but it says that the account is part of another organization

I have tried to delete everything under this account, including lists, contacts, etc. But the error persists.

Please delete the account bob.ehlers@hautespot.net from Campaigns.

PS...I tried calling help line and it just rings no answer. This happens often with Zoho support in general. No one seems to answer the phone.