Walk-Behind Mowers

I recently purchased a walk behind mower (Model HU675AWD). Is there any way to slow down the factory set speed on this mower. Being new to an AWD product, I find the speed too fast to trim around landscaped areas and trees in my yard. I read the instructions on how to speed the mower up after a time when the cables may stretch some, but there does not appear to be an adjustment to go the other way. Any assistance you can provide would be appreciated.