TreasuryDirect doesn’t give you a way to sell Treasury marketable securities — T-bills, T-notes, T-bonds — directly on the platform. To sell before maturity, you first have to move the security to a brokerage account, after which your broker can handle the sale.
The steps are straightforward:
No brokerage account yet? You’ll need to open one before you can do any of this. Most major brokerages accept incoming transfers of Treasury securities without issue.