Step 1.
To clean the outside of your boots, use a soft sponge, some mild detergent/soap, and water. Scrub the boots until they shine!
To clean the inside of your boots, use a lightly moistured towel (preferably white). Wipe the inside of the boots gently.
Step 2.
Once cleaned out, leave the boots to dry. This could take a day or two. Whatever you do, don't use a direct heat source. Direct heat sources and your FUBUKIs are not best friends. Never place them in front of an electric heater/radiator, an open fire, in an electric drying cabinet or in a window that gets plenty of sun on a hot day. If your boots happen to be soaking-wet, you could consider using a boot dryer.
When they have dried out, spray the inside of the boots with some antibacterial shoe spray and leave to “rest”.
Recommendation
While the boots sit and rest, drop down a SmellWell Freshener Bag in them. Bad odor is normally caused by bacteria that thrive in moist environments. SmellWell Freshener Inserts go to the source of this problem by effectively absorbing moisture and eliminating the environment for bacteria and odor to develop. No moisture, no bacteria, no smell!