How to delete and add email ids to unsubscribe list using sendgrid api -

i have problem in adding , deleting emails unsubscribe list. using "https://api.sendgrid.com/api/unsubscribes.delete.json?api_user=your_sendgrid_username&api_key=your_sendgrid_password&email=emailtodelete@domain.com" api delete unsubscribe list, when run gives me success message not able send email email id, have deleted email unsubscribe , can't see in unsubscribe list. when add unsubscribe list, able send emails, can see unsubscribe list. can 1 give me right api