If you decide that you no longer want to include a SharePoint task list in Project Web App, a Project Web App administrator can remove the connection to the list without deleting the list or the site that contains the list from SharePoint.
Note If you have connected a SharePoint task list to Project Web App, and then turned that connected list into an enterprise project by following the steps in Change a SharePoint task list into an enterprise project, when you delete that project, the SharePoint task list remains on the SharePoint site and becomes editable. The connection to the site is no longer listed as a project in the Project Center in Project Web App.
To remove the connection to a SharePoint task list in Project Web App:
The connection to the SharePoint task list is removed and no longer appears as a project within Project Web App. However, the task list is still available for viewing and editing in SharePoint.