https://treasurydirect.gov/help-center/treasury-bills/redeem-reinvest-treasury-bills/
Once you schedule a reinvestment, you can edit or cancel it within the same time frame. For any of these functions, log in to TreasuryDirect, go to the "ManageDirect" page, find "Manage My Securities," and proceed. See Learn more about Reinvesting Maturing Proceeds.
