I have been reading the works of Anton LaVey and I am having trouble finding out what he thought about or wrote concerning the medieval grimoires of the middle ages and if they are practiced within the Church of Satan or if they influenced LaVey in any way. Please Help Me

Read this essay of his, available from the Church of Satan website:

On Occultism of the Past
http://www.churchofsatan.com/Pages/LaVeyPastOccultism.html

In short, if you want to make strictly ritualistic use out of old grimoires, old church propaganda stories, the fiction of H.P. Lovecraft, or even Star Wars, go right ahead. Have fun incorporating them into your rituals. But there's really no need to revere them beyond that use. The Satanic Bible cuts through all the esoteric fluff that you find padding those grimoires and the like, and gets right down to the real components of ritual. Reread the intro to the Book of Belial.

If you find the principles in the medieval grimoires full of power then use it in your rituals. Power is all.