When you signed up to Covve you either chose to sync contacts with your device or to start with an empty Covve address book.

If you chose to sync with your device then when you delete a contact in Covve, it will also get deleted from your phone’s address book - and vice versa.

If you want to hide a contact in Covve but keep it on your phone you can choose to Archive this contact in Cove.

When opting to delete a contact from the Covve app this pop-up will appear, prompting you to confirm that you want to, indeed, delete the contact from Covve and your phone's address book.