The Ford transmission has a drain plug. Just remove the plug and drain, much the same as changing the engine oil. If you want to replace the internal filter you will have to drop the pan on the bottom of the transmission. I don't recommend going through that much trouble. Over the last 40 years I have changed the internal filter on about 4 different vehicles and have never found them to be the least bit dirty. This includes the Ford F53 Chassis in my 2006 Winnebago Sightseer about 2 years ago. I no longer own the Sightseer.
Do be aware that Ford is very specific about the type of transmission fluid, look in the Ford chassis owners manual for the fluid. Do an internet search for "Motorcraft Mercron SP" for a place to buy it. In my area most auto parts stores don't carry it. It costs about $10/quart and you will need 7 quarts.
Hopefully, you are aware that just draining the fluid only drains about 40% of the fluid. The remainder is in the torque converter and hoses to the radiator. You have to go through a flush process to get all the old fluid out. Or do the drain and fill, then drive for 20-30 minutes, repeat the drain & fill 2-3 more times. That will get about 80%-90% of the old fluid out.