How can I re-format a (Windows) 6G Classic iPod with a Mac?

Help wanted. I want to restore/format a 120GB 6G Classic iPod (Windows) that I was given (that is perfectly functioning) to erase all music/info and convert to Mac. Problem is that it is/was formatted for Windows and I would like to format it for Mac, using my old Mid-2011 iMac, that runs on OS Sierra (10.12.6), and has iTunes 12.8.2.3. I wouldn't want to upgrade either my OS or iTunes. When I plug the iPod via USB my Mac-iTunes recognise it and I can see all songs, lists etc, but I can not see the summary or the restore/reformat buttons. Do I need to restore / delete all with a Windows computer or can I do it with my Mac? How? Thank you.