Keeping squirrels away can be a challenge.
But first thing you should do is look around your yard for things that are attracting the squirrels to you yard.
Look around for any fallen seeds, nuts and fruits that have fallen from trees and get rid of them so the squirrels won't be attracted to them in your yard.
You could also scare them by using motion sensors for sprinklers so the sprinklers will come on and spray the squirrels when they enter your yard.
Eventually the squirrels should learn to stay away from your yard.
Jalapeno pepper plants and Garlic can also repel squirrels from areas around your yard.