How do you remove a misfire from a semi auto pistol barrel?

A misfire is a cartridge that fails to fire- at all. Operating the action of the pistol by hand will normally extract the misfired cartridge. However, if you are using misfire to mean a "squib" load, that is different. A squib happens when the primer fires, but ignites none or only a small amount of the powder- and the bullet is pushed out into the barrel- and stops there. THAT needs to go to a gunsmith, who will use non-damaging tools to push the bullet back down the barrel and out. Do NOT attempt to shoot a stuck bullet out of the barrel- will not end well.