A Proposal Type may be edited at any time. However, keep in mind, if a change is made, this will affect all open and closed proposals where the original proposal type was used.
To edit a Proposal Type, from the main menu, arrive at the Proposal Type setup with this path: Setup > Proposals > Proposal Types.
The Proposal Types list will be displayed. Locate the record you want to edit, and then click on the Edit button.
The Edit Proposal Type form will be displayed. Make the necessary changes, and then click on the Save button when finished.