A mosque comprising of two stories was built with the qibla [direction of prayer] and minbar [pulpit] on the second floor. The imam stands on the second floor while the congregation stands on both the first and the second floors.

1. Is it permissible for the imam to pray on the second floor or should the imam's place of prayer be removed and rebuilt on the first floor?
2. Are the prayers invalid if the qibla remains on the second floor?

The prayers of those who pray on the first floor are valid as long as they are able to follow all of the imam's actions.
The right thing to do is to leave the mosque as it, because the location of the imam on the second floor in this scenario does not nullify the validity of his prayer or those he leads.

God the Almighty knows best.