Removing Definitions From Projects
Removing a definition from a project is different than deleting it from the database. When you remove a definition from a project, the reference to the definition is removed from the project, but the definition still exists in the database and thus may be part of another project.
To remove definitions from projects:
In the project workspace, select the definition that you want to remove from the project.
To select multiple items, highlight one or more nodes by using the Ctrl key while clicking the definitions to remove.
Press the Delete key or right-click to select Remove from Project from the pop-up menu.
This action does not delete the definition; it only removes it from the project.