To request a leave cancellation and postponement, you can follow these steps:
1. Address the letter to the appropriate authority, mentioning your details and the original leave dates.
2. Clearly state your request to cancel the leave previously approved and explain the reason for the change.
3. Request to postpone the leave to the next day or a specific date.
4. Express your willingness to discuss the matter further if needed.
5. Close the letter with a polite closing remark and your signature.
Remember to keep the tone professional and concise in your letter. It's essential to communicate clearly and seek approval for the revised leave dates.