The best way is… One, thoroughly “clean” the knife, including handle, with dish washing detergent and none abrasive sponge and “hot, but you can still touch without burning your hand” running water, BEFORE food debris on the knife gets dry and harden. Alternatively, you can use soft cleanser that contain a little bit of chlorine. (AKA, bleach) Two, after washing out all the detergent on the knife, wipe it dry COMPLETELY. Then, use isopropyl alcohol (90% is good, no need to get 100%) in spray bottle. Spray on to the knife, including the handle. Don’t do this on WET knives, you’ll be wasting your time and alcohol. Three, more importantly, regularly bleach your cutting board. It is pretty simple and straight forward. You just need to remember, cleaning always comes first, then sanitize. Same logic / rule applies for washing your hand. Applying hand sanitizer on uncleaned hands makes ZERO effect.