If you are going to terminate the termless contract, remember that you can terminate it impossible. After all, no wonder it is called indefinite. According to the article 699 of the Civil Code of the Russian Federation you can only withdraw your agreement.
You need to insure in advance - even at the signing of the document: include a paragraph indicating the period for which the parties may notify each other of termination of an indefinite contract. As a rule, he ranges from one month.
In order to send a notification, you need in written form to prepare a paper. Be sure to sign it. Then you can use the services of regular mail. Please send your notification letter. The date when the recipient will receive your message and sign it, and that will need to count.
Can submit your notification with the courier. Importantly, the party with which you have signed a perpetual Treaty, signed that she was aware of the termination of this document.
However, if your contract stipulates that you can terminate it voluntarily at the initiative of one of the parties is impossible, you can refer on this issue to the court. For example, in the case of improper performance by second party of its obligations under the contract. You need to collect evidence of the failure of certain clauses of the contract, finding relevant witnesses and make a competent statement.
The court may terminate the permanent agreement even unilaterally. For example, if the other party to the meeting were not. In this case, the copy of the record of the hearing will be sent to the other party by mail.
Alternatively, it is possible to terminate the indefinite contract by agreement of the parties. For this you need to agree with your opponent on the most convenient way to end your business relationship. Consider all the options. You may be able to offer as compensation any compensation. Or you agree on further cooperation on other issues. In this case, if the signed contract will not hold both parties to agree will be much easier.