If it was a coworker wearing the hat, then, yes- I would ask them to take it off. We are not allowed to promote politics of any kind at work. (We re a public library). If a patron came in with one on, I would not ask him/her to remove it. As long as it doesn t have any profanity on it, they are welcome to wear it. Now, if they started discussing politics with us, we have to stop it. We will not stop a regular private conversation- even if it involves politics as long as it s civil and doesn t become too loud and disruptive.