Seeking advice on what reason to provide my work as to why I am leaving the job. The actual reason is because my manager has been hostile towards me.I would write in the following manner: This is a resignation letter. Clearly state your resignation and your last day of work. Be professional and cordial in your tone. Looking to resign with a Unfair Treatment Resignation Letter? Use our resignation letter template for reason roles. You can write a short and simple letter saying what you just said in your post. Don't cite chapter and verse, but don't sugarcoat your reason for leaving. Learn how to write a short notice resignation letter with samples.