Hello @E P , Thank you again for your time and patience throughout this issue.
Looks like this is the current limitation we have. We have shared your feedback regarding delete all utterances at once to the product team.
However, we don't have any ETA or information to share with you at this moment regarding this. I hope you understand.
Regards,
Vasavi
Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.