I don't have any problems with the yoke really.
Smash it waith a hammer so the glass tube & clamps fall off, then stand it on end, point up, & bash it again & the thing separates & two of the coils fall out.

The two left have the 1/2 moon ferrite in them, thats the hard bit I guess.
I smash them but find the ferrite cuts into the Cu wire too much & makes separating them a pain.
Even after checking as I work I find little chips of ferrite.



My other two options are to cut thru the Cu coil on them & pull it off by using a knife or hacksaw.
Thats tough on the knife & potentially dangerous, even more dangerous if you are doing lots of them.

The hacksaw cuts the wires well but also grabs at the wires & makes a mess.

My best suggestion is to use a 4 inch angle grinder with a cutoff disc in it & a glove on my left hand....

I use the worn out 9 inch cutoff discs when they get down to 4 inch dia, after 5 inch dia they get inefficient in a 9 inch anyway.
Its all to do with the 'Feet per second' Not RPM.