The law does not impose any particular form for your resignation to be valid. However, under the law: “the resignation of an employee can not be presumed and must result in a clear and unequivocal intention to resign.”
Also, although you may verbally announce your resignation or by phone, you are strongly advised to do so with a letter of resignation, that it be sent by registered letter with acknowledgment of receipt or hand-delivered to your employer.
A letter of resignation you can prove that you resigned and avoids challenge by your employer because it is dated. Generally, the date of receipt of this letter determines the start of your notice.
Resign resignation anticipated employment contract breaking indefinite work contract without notice
Click on the following link to download this ms word format letter of resignation: