You can resign for any reason you like, and you are under no obligation to disclose the reason.
Short and sweet is the key here ``I regret to inform you that I will resign from . My notice period of YYY starts today and my last day will be ZZZ''. You add something nice like ``I want to thank you for the good collaboration and opportunities I had at ''. DON'T SEND IT YET.
If he doesn't want to serve notice period, he may approach the HR department or his supervisor and request for waiving off notice period. In some organization earned leave or privilege leave can be set off against the notice period. However, the management may decide not to waive off the notice period.
What to do for resigning without notice? Talk to someone from your new job. Speak to your employer. Remain professional. Include questions. Be grateful. Make copies and hand-deliver the letters.
I understand that my notice period is (Notice period) weeks, but I have been asked to join my new Employer (Date requested to start). Therefore, I respectfully request that you waive this notice period and relieve me of my duties immediately.
While immediate resignation is possible, it's generally advisable to provide notice if possible to ensure a smooth transition and maintain a positive relationship with your employer.
I am writing to inform you of my resignation from my position at (Company Name), effective immediately. Due to personal reasons, I am unable to continue working and will not be returning to the office.