How can I add "Closed" transition instead of "Resolved" to Service Desk requests Form?

[Pete P]

Our agents resolve tickets and the requester is supposed to close them after testing the resolution. 

Our service desk request form only gives option to resolve the issue.  How can I change this form to add the closed transition?

I would like "Resolve this issue" form above to link to "Close issue" instead of resolve.

[Petar Petrov (Appfire)]

Make sure the Browse Project permission is not granted to that group in the permissions schemes, associated to projects B and C. Also make sure that any project roles, that are granted the Browse Project permissions do not include the group in question.

The easiest way is to check if a user has certain permission for a project is to use the Permission Helper - see here.