Assuming this is an S50E series.....

imake sure the park brake is completely released
if you have to, remove the link on the rod on the back side and take the linkage loose.
From the looks of the manual and how this brake is made up there is only one way to access the adjuster and that is through the hole in the drum. So this means you are going to have to figure out a way to put something in the wheel lugs like a crowbar and force the wheel to turn around so the access hole is at the adjuster so you can deadjust it. If that is not possible then since the adjuster is at the top take a torch and cut you a hole. (you are going to be replacing everything anyway after you get it apart, a new drum isn't going to make much difference).

otherwise you are going to be stuck getting two long crowbars and just wrenching the hub off.