If your app hasn’t explicitly had the ability to do these administrative tasks built into it, it’s very likely that a non-tech person will not be able to do it.

What you’re describing is often called an “admin panel”, or a “back office”. There are ways to develop these relatively quickly, such as CRUD (Create, Read, Update, Delete) generators/tools, but they’re not as polished as the customer facing UX. For example, using them often requires an understanding of the underlying data model used in the database, and they may not enforce certain business rules automatically, requiring you to manually account for those.