Someone expressing their beliefs that might be different from mine doesn't make them losers. And if you want to cause them physical harm, what does that say about you?
The proper course of action is to inform the store manager. If they are too weak-willed to do anything, that's not your problem. You can make a free market decision not to shop at that store anymore. Nothing brings about change more than lost revenue. When the store starts to look at their books and wonder why they're losing money, they'll have to question their management policies. Are the products bad? Is the service bad? Are people complaining because shopping there is frustrating? That's what voting with your wallet can do.
Also, the store manager can call the police if they still refuse to leave. Getting physically involved to the point of wanting to harm people because they are doing something you don't like makes you no better than them, and opens you up to legal consequences.