The process to delete a Zoho CRM Account would be as follows:
1 - Export all required data
2 - Downgrade to Free edition - you can retain it as a Free for 18 months which gives you access to your data. If your data is impacted by paid features (for example Custom Fields), these wouldn't be visible
Once your Zoho CRM account is deleted you will not be able to recover your data or reinstate it. Hence, make sure you backup any data you require before downgrading or deleting Zoho CRM.