If you no longer use a project or client, you can archive them. This will remove them from any area (i.e. timesheets and expenses) where they are used so that staff can no longer select them to record time or submit expenses claims against.
To archive an old project or client, navigate to the projects and clients tab.
Find the project you wish to archive in the active projects list and click on the admin cog to the right of the page.
You can restore archived projects and clients at any time by clicking the archived link in the top right corner of your active projects lists. Find the project you wish to restore, and click on the admin cog to the right of the page. Select restore client or restore project accordingly.