What I want to do seems like very basic editing, namely, delete a vocal section from a song in itunes. I can select the section I want to remove, but neither the cut button nor the Edit->Remove Special options are enabled. Can I do this in Audacity and end up with a comparable-quality recording, but with a section removed?
Which version of Audacity are you using? (look in “Help menu > About Audacity”).
The current version is 2.2.2, which is available via the Audacity website: https://www.audacityteam.org/download/windows/
If you are using an old version, you may need to press the Stop button (editing not available while playback is just paused, it needs to be stopped).