125-200cc triple clamp nut direction

I have one seized nut, the one on the top triple clamp that sits below the handlebars, if I sit on the bike, do I turn it anti clockwise to undo it and clockwise to tighten it up? I've tried hammering it, both directions and nothing, it's stuck solid

this nut at 2: 07
View: https://www.youtube.com/watch?v=dYUL4siK82o

It is right hand thread.
righty tighty, lefty loosey

You might try some heat. Someone may have used llocktite on the threads. Or if you have access to an air impact wrench.

have no impact gun or the like but just bought a 30mm big wrench/ ring spanner, fits ok but still no luck, I will try heating it up like you said, thanks

used a fan heater, probably didn't do much but a few more tries with the big spanner and it came loose! Then tight again, then loose, tight, finally got it off, bits of filed metal all inside it, I think someone cross threaded it

that's what I was just thinking, surely the stem that comes up through with the thread on the end is made of some stronger metal and the nut is light weight easily broken? It certainly felt very light to hold, this would be the same as the gear shift shaft and the aluminium shifters that fit on it, they seem to wear faster than the shaft itself. So, the stem is made from more solid metal?

usually they ve been tightend up around 12- 20 NM - not more- but the manual will know exact torque settings.
is there any thread left? is it worth re-drilling the thread and put a new bolt in it?

I just tried screwing it back on, have had lower bearing switched for new one, no it won't go on easily, it will turn with force but it just chews up, the stem looks ok thread wise but this top yoke/ clamp the thread in it seems pretty done. Watched some you tube vids on how to change them and all they do is undo the bars, then the very top nut and the top yoke simply lifts off, but this one has to be screwed downwards. If I were to grind away the inside of it so it had literally no thread pattern, would it be safe to slide it straight down onto the stem, ie no thread holding it on, then tighten it down using the top nut only?