My skin and hair became less oily overnight when I quit sulphate surfactants/ all shampoo and went to conditioner only washing. Others find it takes some weeks for their skin to rebalance, sulphates are a powerful irritant known to damage the skin's barrier function and sebum is one method by which the skin tries to protect itself.

Sweat can be removed with water only, the salts are water soluble. I also use Batiste dry shampoo for roots on in between days, spray loads on my hairline and gently wipe away the excess with a microfibre towel.