All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The Sharee’ah ruling on children's dolls has been already mentioned in Fatwa 3643. As for the ruling on decorating walls with images and pictures, it has another ruling different from that of the dolls used for play due to the following reasons:
First: Permissibility of dolls is a concession set by the Sharee'ah to fulfill the children's need to play. It is not applicable to other cases, however. That is because the preponderant opinion is that concessions should not be used outside the sphere that they are made for.
Second: Scholars stated the impermissibility of engraving pictures on walls and similar objects.
Third: Using these pictures in decorations may give the impression that they are exalted and venerated.
Fourth: The children may get attached to the figures illustrated in these pictures, love them, imitate them, and even get feelings of exaltation towards them instilled in their souls. It is clear that this attitude entails many sharia violations.
Thus, our viewpoint is that walls should not be decorated in this way. So you should hasten to remove them.
Allah knows best.