You can stop someone from scheduling Report Builder files. To do so, go to Admin > Company Settings > Report Builder Reports. Every user (who has access to report builder) will show up here, with the second column showing how many reports have the scheduled and how many in total are available. Click on the edit icon next to it, and change it to 0
You can also have email restrictions, so users cannot send reports outside the company email domains.
As for the Library, there is no method to disable the usage. This is a shared space where an uploaded workbook can be viewed by any other report builder user in the company. It is similar to sharing it via sharepoint, or dropbox, or googledrive.
If you are not having the "Company settings" under "Admin", then it means you are not an admin for this organization. You can take assistance form any admin to have this completed or alternatively ask for admin privileges and do it yourself.