You can’t get rid of it, you can only hide it: Microsoft imposes controversial Windows Backup on users::Like it or not, the Windows Backup app installed in Windows 10 and Windows 11 is here to stay, with Microsoft calling it a "system component" that can't be
You also can't use a work or school account, according to Microsoft:
There is also no way to use the backup app with local storage, like an external hard drive; you can ONLY back up to OneDrive with this.
EDITED to clarify: for now, you can still back up to another drive, but it's a different process and the "advanced settings" needed to do so are buried several layers deep.