18yo child has removed himself from Dad's home(Mom is paying support), and is now living with Mom's parents... Child has full-time job, and has been living with grandparents since graduation (around June 1st), so not under care of either parent. Not enrolled in school. If both parents agree on emancipation, can it be done with no questions?

I'm assuming what you are referring to is cessation of support payments. At 18 the child is emancipated legally, in other words living on their own.

If the father is no longer providing custodial support for the child, then the mother can petition the court to end support payments. If the father agrees then the court should rubber stamp it.

However, the kicker here is what is written in the original support agreement.

Order states, 'duty to pay support shall cease at 21, unless emancipated by the court prior to.'

Ok, Then you do need to go to the court. Submit the facts and ask for the child to be declared emancipated and for support to cease.