To Delete Uploaded Image - go to your profile. Click on the 'Images' Tab. Click to select the image(s) you want to delete. Then scroll to bottom of the page and click on 'Delete Selected'.
To Delete Mockup Image - go to the Product page where you want to delete the Mockup. Click on 'Product Media Manager' link above the image. Find the image you want to delete and click on the 3-dots to get the dropdown menu. Choose 'Delete', and that should do it. You'll still have the image available if you want, but it will not be connected to your product any longer.
