You can clean by using some warm soapy water and a small brush, like say a tooth brush or one of those small round brushes that come with some elec. shavers. After cleaning out you can blow out the moisture with compressed air. That stuff in a can for blowing out keyboards works fine. It is not really necessary to take the knife apart. If you do so get a good #10 torx for the pivot and I think it is a #6 for the other torx screws. After all cleaning and drying apply a small amount of lube to the pivot.
A spray can of brake parts cleaner works well on the all-metal knives. Don't use it on plastic, though.
If you do clean with soap and water, I recommend heating the knife with a hair dryer to evaporate any hidden moisture. You can then flush the inaccessible areas with WD 40 and wipe dry. Use a good oil to lubricate the moving parts after the WD 40 evaporates.