The access hole is on the lower backside of the backing plate.
It's oval so pry out the plug and shine a light in and look,there is a toothed wheel inside.
Take a flat screwdriver and turn it (direction I forget,been a few yrs since I did drums) till it's real good and loose.It can even fall out of position,doesn't really matter as long as it's good and loose.
I give a few good taps on the sides of the drum to try and move it a lil front to back,hopefully knocking the pas inwards some.
Now try to pull the drums off,usually I could just by hand,but if not grab that BFH.
Once you go to put it back together and don't know where that adjuster goes,look at the brake pad.....errrrr shoe ( see it's been awhile,I'm try'n to call shoes pads lol ) at the bottom there will be a slot in the shape of [ on the front piece and ] on the rear that adjuster ( --l- ) fits between them like this [ --l- ]
Whatever you do do not get grease or oils on your new pads....errrrr shoes well actually ether or the inside of the drum .