On Marketing > Email > Templates each row (ID, Template, Creation Date) has three icons:

• Preview template (eye) – opens the rendered email in a new tab.
• Clone template (copy) – asks Are you sure you want to clone this template? A duplicate will be created. and creates a full copy including all modules and their settings, with the same title.
• Remove template (trash) – asks for confirmation and hides the design from the list by switching off Save as Template; nothing is deleted.

To remove several at once, tick the checkboxes (or the header toggle to select the page) and use the sticky Remove from templates bar at the bottom. Click a template's #ID to open it in the designer.

Note: cloning does not carry over the Save as Template flag, so the new copy won't automatically show up in the Templates list – open it and switch Save as Template back on if you want it listed there.