Hi there, this may be the most noob question of them all, but how do you actually shut off a glow engine? i have a thunder tiger GP42 attached to a seagull boomerang! lol lol lol

You fully close the throttle. Or you stop the fuel supply but I prefer the first option

You should have a switch assigned as "kill switch" on your radio.
You programe the radio so the engine idles nicely with the throttle stick at bottom low position, when you flip the "kill switch, the throttle barrel in the carburator should fully close = no air to the engine = it stops.
Same thing (closing the throttle barrel) can be done by using the throttle trim tab by trimming the throttle down until the barrel close.

It's important from safety aspect to have full control on your engine and be able to shut it down immediately if you need to!

Adjust your throttle linkage so that when the throttle trim lever is all the way up, the engine idles, when the lever is all the way down, the carb barrel is completly closed. Jim

The answer depends on whether you have a trim *lever* or a trim *button* Some newish computer radios have trim buttons, so you can't quickly move the throttle trim to kill the engine. On those radios, it's very important to program the kill switch like test005 suggested. If you have a lever, you can set up the kill switch if you have one (I find that really convenient so you don't have to find your idle setting again) or just use the trim like gollywock said.

I have an aold attack 4 futaba radio second hand one, its in nick condition and batteries work for hours, but i will not have a kill switch!!!

You can simply use the throttle trim to kill your engine then.