How to unstick left front brake. on 1999 Volvo V70 XC

Car began slowing rapidly when coasting without applying the brakes. Noticed after 10 mile drive. Left front disk sizzling hot. Others cool.

Asked by for the 1999 Volvo V70 XC
You have a caliper that has seized, still recommend replacing in pairs, at least one rotor, brake fluid flush for front and rear and make very sure caliper guide mounts are cleaned/lubed with high heat lube.