Easy to do, fun and interesting. I am using a "Digital High definition 0.45x Wide angle lens with macro" Made in Japan.
Step 1: Matirial
Basically, there are only 2 materials the Wide lent and a small screwdriver.
Step 2: Find the Indentation on the Lens.
Most of the lens has an indentation like the one illustrated on the image, that indentation is to remove the "nut" or ring that holds the lens in place. Take your screwdriver with a flat head and turn the CCV
NOTE: NO NOT FORCE IT.
Step 3: Take the Ring Out.
Once you take the ring out but in a safe place. We are going to use it later. It is fragile and can't bend o scratch. Now the lens is free to be removed.
Step 4: Remove the Lens
Now remove the lends and flip it over. The face of the lens that was facing the inside now has to be facing the outside. Normally you go to see a difference for example: see the difference between the first an second images.
Step 5: Put the Ring Back
Put the ring back in place. This can be done by hand tighten the ring or "nut". In this point you not need the screwdriver only to tighten in the case is need it.
Be careful and delicate with the thread.
The lens may fill loose but if the ring is correctly in place the lens will not fall.
NOTE: TAKE YOU TIME DO NOT FORCE THE RING