The answer is sterilization. It's the top tier of decontamination, the only process that wipes out all microbial life, spores included.
Cleaning, sanitizing, and disinfecting form a real hierarchy below it: cleaning removes visible debris, sanitizing knocks germs down to a safe level, and disinfecting kills most (but not all) pathogens on surfaces. Sterilization is the only one of the four that's built to also take out spores.
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