Police say the man was released yesterday, a day after another man was freed after questioning.
Essen police said in a statement today that neither man "could be linked to plans" for an attack.
Police said they are still examining items seized in the men's apartments.
The Limbecker Platz mall in Essen was kept shut on Saturday after authorities received tips that it could be targeted in an attack tied to the Islamic State group.
German media reported that security officials believe a German fighter who had travelled to Syria tried to recruit people for an attack on the mall.