The speaker (tweeter) cover separates at the interface between the fabric-covered and plain black plastic sections. I use a flat blade screwdriver to pry at that interface where it will not show . . the lower front corner ot the "triangle". The black plastic protrudes slightly there, providing a leverage point for the screwdriver.
Once the cover starts to separate, work it off all around and set it aside in a safe place.
Now, remove the recesssed Philips screw, and the speaker assemply will pull (or fall) off. Use a pocket screwdriver to release the speaker connector, pull it off, and store the speaker assembly with the cover.
The mirror mounting screws are located behind the speaker. However, as I recall, to get at the mirror motor connector to unplug it, the door trim panel must be removed as well. Do you need instructions for the door panel removal?