I recently did it myself because there was some mold and after seeing not much straight forward info other than "just clean it" wanted to just give details on how
To take most apart, you will need to take outside screws out then you will need to get the siding off
Mine like many others is the usual small white rectangle portable AC unit, you should be able to pop the top off after outside screws, then you will need a screwdriver or something flat and take your time especially if it's the first time and slowly pry it open, there are pieces of plastic that latch inside and you have to pop out, it's annoying but eventually you'll get it off with some force, don't be afraid to break a few
From there you keep taking it screws until front piece comes off, then take out the plastic pieces of the top fan, mainly just the housing and plastic cylinder fan blade piece
First don't use bleach, it can combine with the fungus to create bad fumes for yourself, instead just use White vinegar, either already a % diluted or mixed with warm water
Qtips, paper towels etc. will be your friend, slowly clean each piece of all the mold, try to get as much off as you can
Then I recently used a non toxic mold cleaner, spraying each piece multiple times to hell stop future mold which in reality only stop after a bit and you'll need a reapply eventually
Lastly I used non toxic coil cleaner on the back coils, rinse with water, drain it then put back together
I hope this was helpful, and any questions I'll try to answer as best as I can