The Quick access section in OneDrive links to SharePoint sites and libraries you frequently use and follow. Quick access allows you to open your SharePoint files and use the functionalities of a library without leaving OneDrive.
Quick access will always display the default library originally created with the site. If it's unwanted or unused, site administrators can go to the site, select the gear icon (top right corner) > Site contents > Delete the library. Then, Quick access will display all of a site's libraries in one view. If you can't remove the default library, contact the site owner or EASI.