To remove an existing preset from the Insight Timer app, please follow the instructions below:

1. Navigate to the Timer from the app's home screen.
2. Access the 'Presets' section.
3. Identify and select the preset you want to delete.
4. Tap on the three-dot menu next to the play icon.
5. Choose 'Delete this preset'.
6. Confirm your action by selecting 'Delete'.