Gelato mockups can be removed from published listings on Etsy directly through the Etsy platform.
To remove mockups, you will need to log in to your Etsy account and go to the Shop Manager. From the dashboard, click on the "Listings" tab to see a list of all the items you have for sale in your shop. Find the mockup that you want to remove and click on the "Edit" button next to it. On the edit page, scroll down to the "Visibility" section and select the option to "Make Inactive". Click on the "Save" button to remove the mockup from your shop.
Alternatively, you can also delete the mockup permanently by clicking on the "Delete" button on the edit page. Just keep in mind that deleting an item is a permanent action and cannot be undone, so make sure that you really want to delete the mockup before doing so.
To be able to save changes after removing the mockups you might be required to unlink photos first. Please log in to Etsy Shop Manager and go to the listing that contains the Gelato mockup, and click on it to open it. Scroll down to the "Variations" section and click on "Link photos".
Then, please deselect the thumbnails of the mockups that you want to remove and save changes. Once the link between the listing variant and the Gelato mockup has been removed, you will be able to remove the mockups and save the draft/publish the listing.