Is it illegal to put the stone pier at the entrance of the community back after it is removed?

Not illegal. Because the stone pier at the entrance of the community is a prop used by the community property to prevent motor vehicles from entering, residents in the community are not allowed to dispose of the stone pier at will. It is not illegal for users to move the stone pier and put it back. It is illegal to deal with it after moving, which violates the relevant rights of property management.