Yes. The  lever located on the bottom left side of the handshower controls the level of fragrance in the shower.  You can stop the infusion of essential oils at any time by sliding the lever to the far-right "o" position.  Dilution control markings are on the bottom left side on the front of the handshower face:
"o" =  No Fragrance
"III" = High Fragrance
"II" = Medium Fragrance
"I" = Low Fragrance  
You can also restart essential oil infusion by moving the dilution back to your preferred position (III, II, I) .