Viruses are not bacteria. They are not living things. You don’t kill them. You wash them away.
And the flu is a virus...and omicron, delta, and covid are VIRUSES
You are right and I don’t think many know that.
Viruses certainly meet SOME of the dictionary qualifications for “life”. However, if one leans toward defining them as non-life, I’m okay with that: Just expand the definition of “kill” to one more like a militaristic usage of the word. Ie., “kill” the incoming missile or enemy plane.
In that sense, viruses can be “killed” (or at least rendered permanently inactive & subject to molecular decomposition) by:
Moderate (or more, for faster results) heat.
Biological attack.
Chemical exposure (fairly mild chemicals will do a quick number on them.)
Irradiation by (fairly mild) UV light or sunlight.
Drying them out. Recent work indicates that with COVID this happens rather quickly in low humidity air.
Just to be nit-picky. ;-)