How do I removed the brake calliper and refit?

I assume the brake caliper is the area I’ve circled in green. I want to remove everything and put it onto a superlight titanium fork. I’m unsure how to safely remove it and safely put it onto this other fork. Does anyone know what the bolt I’ve circled in blue is? Does it remove the whole caliper and if so what is the torque value for it?

Many thanks

by Tidings_Bearer