To delete a previous edition, please follow these instructions:
Open the app and tap 'Downloaded' at the top
Tap on the edition you would like to delete
Pull the screen down with your finger and tap the vertical dots in the top right corner.
Tap "Archive" at the bottom of the pop-up.
This will delete the edition from your device, but retain your right to download it again at a later date.
If you go to that edition afterwards, you will see that it will ask you to download it as it is no longer saved to your device.