Is it illegal to repair stairs under the window on the second floor?

It is illegal for a property to modify stairs privately. The house design has been formally designed and approved by the design institute. After the change, it will affect the overall safety of the floor. The owner may require the property to stop the infringement, compensate for the losses and restore the original state. Property is only entrusted by the owner to manage the industry, and major repairs need the authorization of the owner.