If you would like to remove audiobook files that you've synced to your Apple Watch, here are the steps to follow:
Remove audiobooks from your Apple Watch using your iPhone:
- Open the Libro.fm app on your iPhone
- Tap on the audiobook cover to open the audiobook details view
- Tap “Remove from Watch”
Remove audiobooks from your Apple Watch directly on the Apple Watch:
- Open the Libro.fm app on your Apple Watch
- Tap on the audiobook
- Tap the 3 dots in the lower right corner of the play screen
- Tap "Delete"