Removing a downloaded movie from your Mac only removes it from your Mac. If you’ve purchased a film, it will remain in your library; you can always re-download it if necessary. You may hide the film if you don’t want it to appear in your library.

Select the media type. Music, Movies, TV Shows, Podcasts, iTunes U, Audiobooks, Applications, Ringtones, and Radio are all options. To remove something, press Delete/Backspace (or choose Edit→Delete).

Merge multiple iTunes libraries to save storage space.

If you choose Remove Downloads, the playlist will be retained in your library but the music files linked with the songs in that playlist will be deleted from your phone, allowing you to save space. The playlist will be removed from your media library (including iCloud Music Library if you use iTunes Match or MUSIC) using Delete from Library.

Songs downloaded from folders on your computer will be removed from your iTunes Library. If the song was purchased from iTunes and downloaded, you’ll just delete the local version. You have the option of removing the track when it’s gone, which will remove it from all of your connected devices.