You must be an Organisation Admin to manage your organisation’s Project Templates. Ask your Admin to manage your organisation’s roles and make you an admin.
Steps:
Launch the My Apps ribbon from the top menu
Select the Project Templates button in the My Apps menu
You arrive on the Manage Project Templates page
Above the tab
The table displays
Column 1: the name of the Project Template
Column 2: names of projects within your organisation that were created using that Project Template
Column 3: Tools - a dropdown menu that gives you more options
Edit: allows you to edit the project template