Rovercan you please correct this termination letter and suggest a good sentence to inform the employee this is a 30 days notice.
We regret to inform you that your employment with .....will be terminated as from 00/00/0000 [insert exact date] - giving you the required 30-day period of notice.
You have been given several* verbal and written warnings with regard to your work performance. Unfortunately, the management has not found any changes or improvement in your work performance. Hence, the management has decided to remove you from your position as a Sales Executive.
* If a specified number of warnings is required by law, change 'several' to 'three' (or whatever).