Is it forbidden to sell the chicken remnants of a company that are not allowed to be sold, knowing that they are not spoiled and are sold as dog food?

If the remnants are owned by the company, it is not permissible to dispose of them until the company disposes of them. At that point, it becomes permissible to take and utilize them. As for selling them, the prohibition of selling during work hours must be observed. Outside of work hours, the interest behind the prohibition should be considered. If there is a legitimate interest, it is not permissible to sell them. And if the prohibition comes from the state, it is even more imperative to adhere to it. If there is no legitimate interest, then there is no harm in violating it, unless there is a fear of harm or discord.