“I’d like the < p > on the content of the post to go away.”
I think, as the old saying goes, the solution is to stop wanting that. Seriously, I’m not clear on how removing the < p > would give you more control over the layout. Maybe if you say in more detail what you want the layout to be like, people could suggest ways of styling the < p > to achieve it.
Another thought that comes to mind is wrapping the whole post in a < div > – markdown knows that < div >’s are legitimate block-level elements, and so shouldn’t wrap the text inside in a < p >. But I can’t think of any reason to prefer a < div > over a < p >.
