Dear :

[company] recently decided to streamline many of its operations. We have been informed that all of our promotions will now be handled by our parent company in [location]. Consequently, We will no longer need your advertising services.

We regret that we have to end what has been a mutually beneficial relationship. We hope that there will be new opportunities for us to work together in the future. Meanwhile, thank you again for the excellent work you have done for us.

Sincerely yours,

[name]

[title]