Write a letter rejecting the offer of job.

Dear Sir/Madam

I am writing this letter to express my thanks for your offer for appointment in the position of Sales Manager with (name of company). It is with deep regret that I have to decline the offer since I have accepted a similar position with another company.

However, I would like to thank you for providing me with he opportunity to have an interview with you, to discuss career possibilities, and to learn about the work of your organization. I extend my best wishes for your company's continued success.

Sincerely,