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:
In Project Web App, click Settings, and then click PWA Settings.
On the PWA Settings page, in the Operational Policies section, click Connected SharePoint Sites.
On the Connected SharePoint Sites page, click the row header for the project to select it, and then click Edit Site Address.
On the Edit Site Address box, select Unlink the SharePoint site from the project, and then click OK.
Click OK on the dialog box that appears, to confirm that you want to remove the link to the selected project.
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.