Reject Task/Change Request

At the moment it's only possible to mark a Change Request as "Completed". I think it would be a positive improvement to add an option to mark a Change Request as "Rejected". At the moment, if we don't intend to implement a Change Request raised by a user, we add a comment to the task explaining the reasoning for rejecting the CR and send an update as email notification. But what do we do with the Task after that? I don't want to mark it as "Completed", as I have not implemented the CR. I don't want to delete the Task either, as we then lose track of the request. So it stays "Pending" indefinitely. It would be great to have an option of marking the CR as "Rejected" and then being able to filter on that in your Tasks list as well.