We would like to delete Zoho desk account

We would like to delete Zoho desk account

Dear Technical Support Engineer,

We have been using Zoho desk and Zoho CRM.
Our Zoho desk is not connect with Zoho CRM.

When we register the user who is registered at Zoho desk to Zoho CRM we couldn't registered him because the message was displayed that he is already registered at Zoho CRM.

We deleted his Zoho account then we could registereded his account at Zoho CRM but he couldn't access to Zoho desk.
We would like to delete his Zoho desk account without delete his Zoho account because we will registerd his account at Zoho desk again.

Could you please tell us that how way we will do it.