Hello,
Try the following :
How do I delete an enterprise project from Project Server?
Project Web Access provides a utility for deleting records from the
database. Follow the steps below to delete a project and all of its
associated documents and issues from the database.
Actions
Logon to Project Web Access using an administrator account
Select the Admin menu
Select Clean up Microsoft Project Server database from the activities menu
Select the radio button for Projects and To-do Lists
Optionally, check the box to delete the SharePoint subweb for the specified
project
Select the project you wish to delete from the grid
Click the Delete button at the bottom of the page
