You can (it is possible to) tear down your FB page and start anew. BUT: your existing information is never really deleted - and this applies whether we are talking about Facebook, Twitter, emails, posts to open forums like this one, basically anything on the Interwebz. Better to change your habits. I'm sure your friends and acquaintances know where you stand in matters of politics. Let it stand at that. (Not everyone needs to know, or cares, what your political/religious points of view are, especially as you accede to officership.) You might consider whittling down the number of friends as well - for instance, removing almost anyone who has never posted on your wall and on whose wall you haven't posted. This, and adjusting your privacy and posting settings, decreases the chances you'll be inappropriately tagged or that someone will post something that could be interpreted by others as inflammatory on your wall.
One of the things you get used to as an officer candidate is not putting your opinion about everything out there.