I am planning to add sodium silicate (liquid glass) to my 13 y/o remanfr engine to stop an internal combustion leak. What is the simplest procedure w/o special equipment to remove all the antifreeze (ethylene glycol)?

Pull the lower radiator hose. Then pull the upper at the thermostat and pour water through the block.

remove the drain plugs near the oil pan.
be prepared to clean out the rust and sediment.

Also do that on a NEWLY hot tanked or sonic cleaned block, cuz that gunk is still there even after cleaning.

There is a drain at the bottom of the rad. Sometimes they get plugged though if now used often.

Pop off the lower rad hose and take off the rad cap. Once its done spilling out, take off the heater hose on the water pump (disconnect only the end on the water pump) and hook it up to a garden hose and turn the water on... let it run like that for a good 10 minutes and it will push EVERYTHING out of there... all the antifreeze, any loose sediment/corrosion, buildup, etc. Then after that, hook up the lower rad hose and let the water go in through the heater hose again, just as you did before, with the rad cap still off. This will clean out the radiator very well.

Works great, especially for heater cores if you alternate between the inlet/outlet on the heater core.

If you simply pull the lower rad hose you will only drain about 1/2 the block's coolant (but all the rads coolant) Like stated above you need to remove the coolent plugs on the side of the block, they are just above the oil pan and just behing the motor mounts. Also I would suggest a new antifreeze mix when refilling the system/