Dear Md. Rashedul Mostafa, If the employment is for a fixed period and the duration of the employment is properly mentioned, you may simply send a letter to the employee regarding the discontinuation of the employment contract.
Issuing the Letter
When issuing the letter, in the first paragraph, provide a reference to the employment contract, such as the contract number and date. In the second paragraph, state that the contract is set to expire on _____ and that the administration of your company does not intend to renew it. However, when sending the official communication, please verify if the notice period terms are specified in the contract and, if so, adhere to them.
Thanks,
Dinesh Divekar