Within an estimate, you can change the status for individual line items or in bulk. The status of line items is found here on the Estimate overlay:
Clicking the status button next to each line item lets you change that line item to a different status. This button toggles through all the statuses—Draft, Quote, Won, and Lost. Any line items with a status of Draft cannot be sent to the potential client.
To make a bulk change to statuses, select the check box for the line items, then click the appropriate status button at the top of the table.