Note: Only quotes with the stage Draft can be deleted.
Open the desired draft quote. In the Contract pane, click the ellipsis (...) button and select Delete:
The Confirmation message box appears:
The quote is removed from the Quotes list. All content related to the quote is deleted, including the task board.
Note: If your quote came from a deal or opportunity in HubSpot, Salesforce or Dynamics 365, it is also removed from there.