Closing of your bank account is as systematic process as is opening it. It requires a proper request from you to your local bank branch manager to close your account for reasons you are required to explain in your request letter. It can be that you are moving to another place, or may be to another bank.
Start your letter with name of your local bank branch manager. Do not forget to add title i.e. Mr. before the name, which should by followed by the complete address of your branch. Generally, the name of Br. Manager and address is typed/written on top left, just below the letterhead, if you are using one. Do not forget to mention the date you are writing the letter on.
Body of your letter should be started with a reference, if you have received a communication from your bank and are writing your letter to respond to it. Otherwise, start the body with an introduction about you and your account, covering all details.
Once you are done with the message that you want to close your account, do not have any pending issue, give your bank details of further contact, especially if you expect to receive a check from your bank etc. Also, give details of another account, which you want your bank transfer your money to or any other detail you think is necessary for your bank to contact you at.