Resignation letters should use the formal greeting: "Dear". The first sentence in the letter should state that you are resigning and when.Here are 3 examples that you can use for resignation letter as Assistant Professor -. You'll have to submit a formal resignation letter. Here are 3 examples that you can use for resignation letter as Visiting Assistant Professor -. The appointment to a tenure track position is set forth in the letter of offer. Newhall Bldg, Room 3315. Required Documentation. Start with a statement of resignation: Don't try to build up to the news or share it indirectly. Complete any exit procedures: You might need to complete an exit procedure.