To remove a beneficiary, simply go to the Profile page of your Upromise account, click the <x> by the beneficiary you wish to remove. Then click the <Save Updates> button.
If there is a 529 College Savings Plan account linked to the beneficiary you want to remove, you will first need to inactivate or remove the account. Inactivation or removal of the account will prevent any funded earnings from transferring to the account. You can manage your linked accounts from the Profile page of your Upromise account.