Is it permissible for the brother to sell his share of the inherited house, which has been divided by floor between him and his sister?

If the property is divided among the heirs according to Islamic law, each heir independently owns their share and has the right to dispose of it through sale or gift. If the owner of the ground floor wishes to sell their share, they are permitted to do so, and the owner of the upper floor has the right of pre-emption, and vice versa.