Here is a sample letter acknowledging the termination of contract.
To [Recipient name]
Dear, [Recipient name]
This letter is to inform you that we no longer require your services as of [Date]. We thereby consider this a termination of the contract as per the minimum notice required according to our agreement. Although your company has provided excellent service in the past, we have decided to terminate our contract with you due to [Reasons]. Following this decision, we will no longer do business with your company. All pending orders should be delivered before our contract is terminated officially. Additionally, outstanding payments, if any, will be cleared by [Date] provided we receive the relevant invoices by [Date].