During Your Lifetime
Your beneficiary has no ownership interest or rights to the money in your bank account while you're alive. She can't withdraw the money, and you can change your mind and take her off the account if you want to. It's yours to do with as you wish because the payable on death designation, or POD, doesn't kick in until your death.
After Your Death
After your death, your beneficiary needs only to provide a copy of your death certificate and a form of ID to take possession of the account. A possible complication might arise, however, if you leave more debts than assets with which to pay them. In some states, the executor or administrator of your estate is authorized to claim assets that do not pass through probate so as to pay as many debts of the estate as possible.