How to delete/remove custom ringtones (tones) from iPhone in iTunes 12.7?

As of iTunes 12.7, Apple now advises manually adding custom ringtones to iPhone per their support article [here](https://support.apple.com/en-us/HT201593) . Apple's instruction is to drag and drop tones from Finder to the "Tones" section of my device in iTunes. This method works to *add* tones to my phone. However, I can't discern how to **remove** ringtones from my phone. - I've tried clicking the tones in iTunes and pressing delete, without and with various modifier keys. - I've checked the contextual menu under control-click (right-click) of the tones in iTunes. - I've tried dragging the tones out of iTunes. - I've poked around in iPhone settings and iTunes menubar and prefs. - I've tried deleting files from my Mac at ~/Music/iTunes/iTunes Media/Tones/ and re-syncing my iPhone. Any further ideas? Thank you.