A previous thread showed 'carbon fiber' wrapped side mirrors. Will the covers pop off? I tried to find securing screws and do not want to force anything unnecessarily as these are likely hard to find as replacements.

 

I have not removed the X100 covers in a few years abut the X308 should be about the same procedure.
Remove the glass mirror insert and then press the mount 'pegs' from inside. There will be metal inserts to capture the pegs and they might follow the cover or might stay in the housing.

The glass mirror just clips into place with flexible plastic strands. Pull the glass in one direction and release the opposite side.
Remove heater wires if equipped.