It is generally not illegal to tell the police to leave your property, and the police are not allowed to arrest you just for telling them to leave. However, if the police have a valid reason for being on your property, such as a search warrant, and you interfere with their ability to conduct their search or investigation, you could potentially be arrested for obstructing justice. It is important to remember that the police have the authority to perform their duties and that it is generally best to cooperate with them. If you have concerns about the police being on your property, you can ask to see a warrant or seek legal advice from a qualified criminal defense attorney or law firm.