Does the property have the right not to let the owners hang banners behind the second floor?

The property has the right not to let the owners hang banners.

Make outdoor slogans, signboards, banners, exhibition boards, etc. You need to declare outdoor advertising in the advertising section of the industrial and commercial department first, and then go to the urban management department for approval. Without these procedures, the property can be stopped. If the stop is ineffective, you can report it to the urban management. You should not go through any formalities.

Although it is only a banner, it also belongs to the scope of outdoor advertising and needs approval. Unless you hang a public service banner.