Sterilization
Sterilisation
If you kill bacteria you are performing sterilization. You're killing those bacteria.
さっきん
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own. Watch out for the shortening.
トイレを殺菌する一番いい方法は何ですか？
What’s the best way to sterilize a bathroom?