Windows 10: how to select multiple disks (in order to to eject them all at once)?

Solution 1:

Windows Explorer allows to select more than one disk, but the Eject option is then not shown in the context-menu. This is most likely by design and there is no point in reporting it to Microsoft, except as a feature request.

If your wish to eject all DVD drives in one go, see the post
How to eject multiple devices simultaneously?