Dear Mr./Ms. Bossname,
Thank you for accepting my resignation effective in two weeks’ time.
I understand that you belive you would find an exit interview to be valuable to yourself and the firm. Unfortunately, at this point, I don’t feel that I would have much to add. Or, more accurately, based on my experience with the company, the feedback I can offer would likely fall on deaf ears.
My remaining time here would be best spent handing off my projects and helping to train my successors.
Regardless, thank you for the opportunity.