Why should private property slow you down when you are willing to see the Constitution trampled on, willing to allow the belittling of our American troops, willing to see all social norms and respect for others abandoned, willing to have a sexual predator in the White House, or see our allies abandoned while our enemies are glorified.
Signs on PRIVATE PROPERTY are PRIVATE PROPERTY. You violate the law when you damage or remove them. If you are so insecure that a piece of cardboard threatens your mental stability, please seek counseling. You are a danger to society.