I had accepted an offer with a company which I later decided to reject. What is the correct way to send a declining letter?

Our approach is long range. Our solution would be to work with the employer with whom you signed a contract in order that you not ruining your name for the future. We have seen that people in industries speak to one another. They speak about employees who signed on with company one and then moved to company two without properly telling company one. You, as an employee, do not want to have a bad reputation. We would recommend that you negotiate a proper settlement with company number one so as not to tarnish your reputation. You can then begin employment with company number two. If you need help with this effort, please contact us.