I need to remove "Made For Email" templates from SharePoint.

How about just making them less visible? To do that, create a custom template for news pages based on one of the other page templates (not the "Made for Email" ones). Then, select it as the default for the site from the template picker when you are creating a page. This will make it so that users see your template first when they are creating news posts. The Made for Email templates are still there, but they are "hidden" behind a tab so that users would have to consciously pick them if they wanted to use them. This has been a game changer for my clients who do not want news publishers to use the "out of the box" templates. That said, you can also create your own template from one of the Made for Email templates and add metadata as well if you want to use it to curate posts - but if you prefer the "standard" page structure, you can just create your own template from one of the other "out of the box" ones. The key is to set your template as the default. That will bring up the one you selected and any other custom templates on your site before the Microsoft ones.