We support our grandson's college education. Can we use this as a deduction

No. Only the person who claims the student as a dependent (presumably the parents) can claim a tuition credit or deduction.  But, they may count what you paid, when claiming the credit.  If the student is not a dependent, then he can claim the credit, again using the amounts you contributed, in the calculation.

Only the parents or legal guardian can claim the student as a dependent, as well as any education expenses they may qualify for. So if you have not been the legal guardian of the student for at least the last 6 months of the tax year, they don't qualify as your dependent. Yes, there are exceptions. But if any applied I'm confident you would have made them known.