Answer:
This is a State law issue and the bank should not get embroiled into the middle of this. In Texas: "the custodian shall transfer the custodial property to the beneficiary on the date the beneficiary attains 18 years of age". The custodian has no right to do anything else with the money. As far as I know, this is the same in every State, the only difference might be the age at which this occurs.