Open car door and lower window. Prise off the little bit of trim on the inside of the door directly behind where the wing mirror is fitted to door. You will then see the bolts that fix the mirror on. Undo these, normally they will be Torx screws. When the bolts are removed, gentle pull off the mirror body and this will draw through the electrical wiring harness connector. Pull apart this connector and remove the mirror. Replacment is the reverse of above.
Rupert, June 2020