Replacing gaskets

[hect75]

Hi, , I need to replace the leaking gaskets (cylinder head and cylinder) but I am not sure if draining oil before taking off the cylinder head is needed. Screws at the cylinder head are loose and learned that oil is leaking slowly since I cleaned an oil spot under the bike. I know Spud drained the oil when rebuilding the engine but not sure if needed when doing the cylinder gaskets.