Note: You can also change the retention period to delete older recordings.
To delete a "Screen Capture" recording:
Click on the specific portion of the timeline you want to delete in order to select it
Hit the delete key on your keyboard
Confirm you want to delete the selected recording
To delete a "Mic/Speaker Capture" recording:
Click on the three dots in the upper right hand corner of the transcript
Click on "Delete transcript", which deletes the audio recording and transcript from your disk
Confirm you want to delete the selected recording