I heard from shaykh al Fawzan that whoever mocks the the beard is a kaafir. My parents are anti salafi, they know the ahadith of the beard but mock salafis and them having long beards. So do I have to declare my parents kuffar or is this something that only scholars must indulge in.

A'udhu billah, may Allah Subhanahu wa Ta'ala protect us. How could you utter such a thing? If they're making fun of how you look and so on and so forth, this is not disbelief that gets someone outside the fold of Islam. What gets somebody outside the fold of Islam is mocking Islam itself, and mocking the beard as a mockery of Islam itself. We shouldn't just hear a general fatwa that we don't understand anything from, and then go and start making takfir of people—and not just any people, but our own parents. We seek refuge with Allah Subhanahu wa Ta'ala. Please learn this rule from me: do not apply general rulings upon individuals by name. There is a huge difference between the two. A scholar could be mentioning a general thing, a general ruling, however, that is different from applying it to an individual by name. This is just like Shaykh al-Islam Ibn Taymiyyah (rahimahullah), Ibn Uthaymeen, and the people of ilm have said.