To end your current service agreement, locate the termination paragraph in your agreement. This paragraph usually states the conditions for termination, including:
a) Terminating the agreement with 60-90 days written notice for any reason, or
b) Ending the agreement immediately due to a reason such as negligence.
If your contract term has ended and there is no automatic renewal clause, you are on a month-to-month term and can give 30 days' notice.
Be sure to thoroughly read the termination paragraph, as it may specify that notice must be given via certified mail. In such cases, some boards opt to send a termination notice via email, indicating that a formal, mailed notice will follow.