1. Put a paper bag over your head
2. Grow a beard
3. Move to a very hot country so your face will be brown all over
4. Try lemon juice - it's a natural bleach.
I am guessing they might be what is called "Liver Spots",nothing to do with the liver by the way, and quite harmless(if unsightly).
I have them on my hands and find that Evening Primrose cream (any cheap brand works) will bleach them out.
I have removed many types of lesions including one I had on my neck for 30 years by dabbing it with TCP. A number of applications were necessary and won't disappear overnight so be patient. The one on my neck has never returned after 5 years.