fab fab fab

im about to order my hardtail for the bike an had a couple questions. in this first picture there is a plate right where the hard tail goes. am i suppose to remove this or weld directly to it? https://mail.google.com/mail/?ui=2&ik=e2502a12c7&view=att&th=12a1195d2285d976&attid=0.1&disp=inline&zw...