You must remove (or at least pull away from the door) the door card which contains the speaker grille. The speaker itself is bolted to the inner door panel.
Though it's not for the front door, this guide has some useful pics:
Do you mean the small tweeter in the mirror panel? Tweeters buzz and Mids fart.
If so you have to prise the top outwards. This will release a clip then push upwards to disengage the stabilising stalks.