document.querySelector("tr.titlebg > td").style.visibility = "hidden";
document.querySelector("td.windowbg > table > tbody > tr > td:nth-child(2) ").style.visibility = "hidden";
I didn’t check because my PC is bricked (sadly

), but I feel like this may end up removing stuff it shouldn’t in some cases (i.e when there is a table in the post), so be careful.