A resignation letter should be short and straightforward.
As a minimum, it should include
- the date it was written
- the name of the person it is addressed to
- a statement that you are resigning
- the date when your resignation is effective
- the date of your last day
- your signature and name.
If you can say some positive things about the employer in the
letter, do so. Perhaps you can thank your employer for the
opportunities the job gave you, or wish the company well.
However angry or upset you feel about the way the company has
treated you, don't be tempted to put these feelings into the
letter. Remember, this letter will remain in your personnel
file for future reference; you want it to represent you at
your best.