To delete a contact in an Agent Account, head to the Contacts page from the main navigation.
Look for the contact in question in the 'Contacts' area on the left, then click the Delete button and complete the confirmation step to delete the contact.
CRM Contacts (identified by the "CRM" logo to the left of the contact) cannot be deleted in the rezora interface. CRM contacts would first need to be deleted in the CRM, then pulled into rezora via a fresh Sync.
Note: Deleting the contact will not remove the "bounced" or "unsubscribed" status from a contact.