Final answer: In terms of a real estate transaction, the ability to cancel a listing during the term of the listing agreement primarily lies with the seller and the broker.
If you're set on canceling, send a formal request in writing, either via email or certified letter. Be sure to include your property address, the date, and a clear statement that you're terminating the agreement. If you want to work with a different agent in the future, be clear about the termination timeframe.
Reasons for termination might include an agent's unsatisfactory performance, the seller changing their mind about selling the property or a mutual decision to otherwise end the contract.
Both principals to the listing agreement have the power to revoke the contract at any time. They do not, however, always have the right. That is, client or broker may cancel a listing but remain liable for damages to the other party.
The seller can allow a listing to be canceled during the term of the agreement. The seller, being the owner of the property, can decide to withdraw his or her property from the market.
A listing agreement should include a termination clause to outline conditions under which the property owner or real estate agent can end the contract early.
All that is required in California is to notify the listing agent in writing.
The easiest way out is to sit down with the real estate brokerage the realtor works for and discuss breaking the agreement. Many reputable brokerages who wish to keep a favorable relationship with your business will agree to peaceful contract termination.