As time goes by, your iTunes library can become more and more cluttered with music that, for one reason or another, you no longer listen to. Unless you go out of your way to perform a manual sync every time, that unused music will be wasting space on your Apple devices, so it makes sense to remove it from the library; if hard drive space is a concern, you'll also want to delete the files themselves.
Launch iTunes and click "Songs" to show a list of all music in your library.
Click "View" and select "Show View Options" to show a list of available sorting methods. Check the "Plays" and "Skips" boxes and click "OK."
Click the Plays column
Click the "Plays" column heading twice to sort your music by the number of times you've listened to it, with the least-played songs at the top. Look through the list and identify songs you want to delete from iTunes and the hard drive.
Right-click a song you want to delete and select "Show in Windows Explorer" to open the folder that contains it, with the specific file selected. In theory, you need to do this for each song individually; in practice, songs from the same album are likely grouped together in the same folder in your hard drive, so you'll have an easier time.
Delete the song files in Windows Explorer
Delete the song files in Windows Explorer, if you want to remove them from the hard drive. Do this only if you no longer need the songs or if you have a backup. Close the folder and switch back to iTunes.
Select the same songs
Select the same songs in iTunes and press "Delete." If prompted, click "Delete Songs" to confirm the deletion from iTunes.
Click the Skips column Skips heading
Click the "Skips" column heading to sort your music by the amount of times you've skipped past it, with the most-skipped songs at the top. Look through the list and delete any songs you want to get rid of the same way as the least played songs.
Click "View" and select "Show Duplicate Items" to display a list of songs with a matching title and artist. Alternatively, hold "Shift," click "View" and select "Show Exact Duplicate Items" to display a list of songs with a matching title, artist and album name. Look through the list and delete any songs you want to get rid of the same way as the least played songs.
If you want to remove files from iTunes but not the hard drive, skip the steps to find and delete the files in Windows Explorer.
Information in this article applies to iTunes 11. It may vary slightly or significantly with other versions.