Currently Remento does not support editing or trimming videos within the app. You can always export your video and edit it with other tools.
Once you have started recording within a project, you can no longer delete individual prompts. You can still rearrange prompts or add new ones to your project.
Please send us an email or contact us through the app or our website if you have specific feature requests or preferences related to editing (or any other feature). Your feedback is greatly appreciated as we develop these tools.