When you have saved a page as a template you can always access it from Workspace manager > Templates > Page templates. To be able to edit a page template, you need to be an admin of the page template.
Steps to edit a page template:
Navigate to Workspace Manager from Admin menu
Or if you a participant in a workspace navigate to "My workspaces" from User menu
Click on "Page templates" under Templates
Find the template by browsing or searching by keywords
Click on the three dots "..." next to the template name
Click "Edit template"
Login to the page template if needed
Start editing the page template either by:
Editing the page by clicking "Edit page" on the top right corner
To edit the template settings click "Template settings" on the yellow top bar
