A requester sends a helpdesk case. It is assigned to a technician.

Technician resolves it. An e-mail is sent to the requester with the resolution along with the link to close the case.

If Requester is not satisfied, he can reply to the e-mail so that the case is re-opened. (and add cc)

However this e-mail is going to contain the link of closing the case.

This is allowing the technician to close the case. And the helpdesk case log will show that it was closed by the requester and not the technician.

how we can only allow the requester him/herself to close the request.

thank you