You can export the collection, the exported collection is a JSON format.
Then you can open the exported collection.json file in an IDE (for eg. VSCode), and you’ll see that each request has a property called auth.
Just find all (VSCode lets you do a multiline find and replace) and delete the entire auth object, and then import the collection back into Postman, now all the requests will be inheriting from the parent (i.e collection in this case)