Allow your cleats to dry thoroughly by placing them outside in the sun for the day to help get rid of some of the odor.
Fill two athletic socks entirely with cat litter to replicate a foot and tie the sock end in a knot to secure the litter in place.
Set the litter-filled socks into the cleats as if they were your feet, fitting them snug inside of the shoe to absorb any additional odors inside the cleats. Allow the socks with litter to stay in your cleats for a few hours or overnight.