All listing
contracts have expiration dates. When is yours?
If it is not coming up soon, tell the agent and/or his
manager that you want to cancel your listing. Often they will
let you cancel easily, since they do not want to build ill
will in the community.
If they won't, you can always pull your home off the market
until the listing contract expires.
You might want to read "Five
Reasons Your House Hasn't Sold."