Just to be clear on your end goal -- Do you want to be able to remove the VTT file (The VTT file is just the text transcription of the audio of your meetings) that is in a format that makes it easy to upload the MP4 video of the meeting and the VTT file to have captioning on other platforms or just inhibit the transcription from showing up with the Recorded Meeting?
GOAL -- Remove the text transcription for any playback of your Recorded Meetings / Prevent download of text transcript
* I believe you can inhibit the Text Transcription from showing up in the playback of the Recorded Meeting if you Edit the Recorded Meeting (click on the 3 dots on the line of your recorded meeting, choose Edit and uncheck Transcription.) -- I attached the dialog that I see when I edit a recorded meeting. If I uncheck transcript from the list, it no longer prompts me when I click download to choose whether to download the MP4 video and VTT (text transcript)...it just downloads the MP4.
GOAL - No text transcription of your meetings should exist anywhere in the Cisco Webex Cloud
This would probably be a Cisco TAC incident -- I don't see a way to just purge the text transcription of the Recorded Meeting.