Constraint on Copy To function for users that have left the job role

We have a need to use the Copy To function on our tasks from one project to another. However, if a user is no longer a part of that job role it will not allow us to move that task over. I don't want to clear all task constraints because then that removes the job role and I cannot mass assign the new project. Is there a work around to override those tasks where the user is no longer in that job role OR a way to clear assignments back to the job role rather than the assignee? Thank you