To make super clean by removing dirt, germs, and bacteria; disinfect pruning tools to avoid spreading disease.
Merriam-Webster Online Dictionary
sterilize (verb)transitive verb
to make as - sterile
a) to cause (land) to become unfruitful
b) (1) to deprive of the power of reproducing - surgically sterilize cats and dogs
(2) to make incapable of germination
c) to make powerless or useless usually by restraining from a normal function, relation, or participation
d) to free from living microorganisms
sanitize, disinfect, purify, decontaminate, cleanse