Why do you think that?
If you starting looking at stuff under Library, there are probably thousands of things there you (or I, for that matter) don't know what they're for. That does not mean they are not supposed to be there.
To be clear, there are no "users" under your Library folder.
If you have any cause for concern, like your mac is not working as it's supposed to, please tell us what is happening. Don't just go looking under random folders, as nothing there makes sense to most of us, but it is there for a reason.
If your mac is not working properly, give us actual information: Please run the diagnostic program Etrecheck and post its full report here. You can get it from the developer's site at etrecheck dot com. It is free.
Use the "additional text" button and paste the report into the text box.