I'm very familiar with adding Post Functions to alter an issue during a transition. The problem is that I can't seem to find a way to remove one particular label during transition to Resolution. I can clear the entire field, but that is not desirable.
I have also tried to create a Condition to prevent Resolution of an issue if the label is present, but this didn't appear to work either. A few comments by Atlassian employees imply that Conditions can't work with the system Labels field.