In order to delete a recording from the Helix TV app :
1. Open the app and go to the menu (three lines on top of each other in the corner)
2. Go to "Recordings"
3. Select the recording you wish to delete and go to the recording's info page
4. From the Options button, select "delete recording"
The specific wording and interface may vary depending on the app's version and device type.
I hope this helps!