单方面解约英语

因故解除合同the contract was terminated due to unforseen circumstances. (不能预知的原因）因生产经营条件变化等原因而解除合同the contract was terminated due to changes in production and management conditions etc.

terminate a contract

毁约英语break a contract;break one's promise

cancellation of the contract

Breach of contract

因故解除合同The contact is terminated for some reasons.因生产经营条件变化等原因而解除合同The contact is terminated for reasons such as the change of manufacturing and management condition, etc.