No it can't. Saliva has enzymes in it, enzyme means: "in life"-alive. Shampoo substances are dead, or chemical combinations which were never alive.

By that logic any cleaning detergent also can't remove blood, sweat, or other bodily excretions from any surface?

And also by the same logic, chemical reactions in general are impossible outside of life. E.g. a fire.

Enzymes are pretty common in laundry detergents and probably also shampoos.

Enzymes are biological substances, but they aren't living organisms. Hence why they are in my dried powder detergent and the like.

The word "enzyme" comes from the Greek words "en-" (in) and "zymē" (leaven), coined by German physiologist Wilhelm Kühne in 1878 from the German word Enzym.

I think you are confusing testosterone and DHT (dihydrotestosterone), which is a testosterone derivative and is not testosterone itself. Shampoos that contain anti-DHT chemicals like minoxidil can block DHT from attacking your hair follicles but don't eliminate it from the body.

A detergent probably can. On that will be labeled as shampoo, which is intentionally gentle, to not remove too much oil from your scalp (which causes excessive oily hair, since it's regulated with a feedback system by the sebaceous glands), maybe not.

Both of you should provide evidence.