How to disassemble a mechanical keyboard as shown

I think you mean how to open the shaft cover of the shaft on top of the PBC board and take out the cross shaft core, right?

If so, I made my own keychain opener as shown in the picture above, so it looks like this, and then stretch the bend down to the bottom of the foot and lift upward to open one side, and then in the same way to open the other side of the shaft, and then the shaft cover will be opened

If you soldered the whole shaft, there's no need for that kind of trouble, just use a curved tweezers and stretch it under the foot, and then open it. Just stick a pair of curved tweezers under the foot and tilt it upwards and it opens up

Oops, is that Mura upstairs?

I think you're the one who doesn't get it. Isn't the cross cap what you're talking about the cross shaft that sticks out, and that's what we're talking about getting out of this thing?