Glass is held onto the mech via clamps - there's two holes in the door skin, with rubber covers that you pull out, where you can access the clamps. Each has a 10mm bolt to tighten/loosen - don't undo it the whole way or you'll drop it in the door. Only needs 3 or so turns. Loosen both, hold the glass, lower the mech. Tilt front edge of glass forwards and lift out the door. That's as far as my expertise goes: I probably have replaced a Focus mech at some point in the last 15 years but I couldn't tell you how to remove it blindly. Probably riveted in (most are, but might be held in with bolts. If the motor is on the outside of the door skin, you'll need to remove that first (usually three or four torx screws) and unbolt/drill out mech rivets and rotate mech and until you can get it out the door (probably through an access panel rather than the top. Of course, if the motor is on the outside, you won't need to remove the actual mech (assuming the motor is at fault because you hit it - I'd start by replacing that, and inspecting the teeth on the mech to check none are chipped or missing)