Going by the photos that looks too far gone to me... you might try scratching the bark of a branch and seeing if the cambium layer is still green. If still green there is a chance. I would then try heavy pruning, fertilizer (probably something quick acting and with micro nutrients like Miracle Grow), and ensuring there is moisture in the soil. If the cambium layer has turned brown then the tree is most likely dead and should be removed and properly disposed of if disease is suspected.
It doesn't look like there's any life left in it. I was looking around the base for some suckers growing from the roots (assuming the tree isn't grafted to begin with) but there does not appear to be any.
