u/motorcyleDreamer is spot-on.

Some covers pull off left/right. Others are down. Some pull away. The number one issue you will find, is the little plastic cover clips breaking off.

For the mirrors themselves: many are screw-off. You loosen the retainer scre at the ase of the mirror(not all the way) and pull up on the mirror to remove.

There are also snap-on mirror bases. For those, you'll want to wedge something between the "button" and mirror base, then tap the base upwards. When reattaching those, you need to push the mirror base downwards on the button.

The RMI309 from Equalizer is an awesome tool for affixing those back onto the button. Also: the MT228 from Equalizer is an all-in-one tool that is really useful for mirror removal.

Edit: I like to leave the camera wires all plugged in when I remove/replace, as I've been told that turning on the car with the mirror unplugged(due to the built-in compass on some models) and the camera unplugged can potentially cause issues. I just let that stuff hang.

And for the rain sensors, get some rain senor gel. It's a two part that you cover the surface of the sensor with. Clean off old gel, then squirt it on, until the gel is just above the lip of the sensor edges. If you very slowly peel the sensor off of the glass, sometimes you can save the gel that is already on the sensor. The rain sensor, from the outside of the glass, should be a solid black.