Archive, email notification

Hello. I would like to remove the Archive field on my online store and on the product pages. I have already tried everything I found on Google, but nothing works. When I try to modify the .php file, nothing happens, and the entire code just appears on the website, visible to all visitors. Any idea how to fix the issue?

I also have a problem with email. Once someone make an order, I do not get an email notification that I have received an order. On the other hand, customers get confirmation email. Please help ??

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