What did the Germans do with the wall after they tore it down?

Answer: Re-purposed it and auctioned it off

History - A piece of the wall stands in the bathroom of a Las Vegas casino. 
Official demolition of the Berlin Wall began in the summer of 1990. More than 40,000 wall sections were recycled into building materials used for German reconstruction projects, but a few hundred segments were auctioned off and are now scattered around the globe from the Vatican gardens to the men’s room of the Main Street Station Casino in Las Vegas, where urinals are mounted on a graffiti-covered wall segment protected behind glass.

Cold WarOld Glory