public void SetDirty( 
   bool dirty
)

Public Sub SetDirty( _
   Optional ByVal dirty As Boolean _
) 

Parameters

dirty

(optional) The project's new dirty state. true indicates changes have not been saved; false indicates no changes have been made. (default value = true)

If the project's dirty state is set to true, you will be prompted to save changes when another project is opened or when you exit the ArcGIS Pro application.

Target Platforms: Windows 10, Windows 8.1

Reference

Project Class
Project Members