Is it permissible to establish a company with an activity similar to that of a company in which one is employed, given that the work methods differ?

The tenancy contract is one of the binding contracts that cannot be rescinded without the consent of both parties, except for a legitimate excuse. Therefore, it is not permissible for the questioner and his colleague to rescind the contract and establish a private company during official working hours. However, outside of working hours, there is no objection to engaging in any work, including opening a similar company.