When reviewing the Mail Templates in the Design Studio you will see different set of icons.
Either the template was created by PRINTgenie or a PRO that you may have signed up under.

If it's your template, you will see a pencil icon as show in the samples below.

Super Admin or PRO Template.
You can order this template as-is in the Marketplace, however if you want to edit it, simply click on the "..." and duplicate.
Once you duplicate it, you own it and can do anything you wish with it.

Users Template.
Once you duplicate a template it is yours to do whatever you wish with it.