Instead of deleting, you can also "Exclude" cards.
Go to the study screen. If you want to exclude a card, tap the bottom-center button, then "Exclude". These cards will be excluded from study the next round.
If you want to delete cards, from the study screen, tap the icon at bottom-right (looks like two cards). This will take you to "Cards" screen.
You should see + and "Edit" at top-right.
Tap "Edit"
If you are using iOS, you can tap on red circle at left to show a red delete button.
For Android, after tapping "Edit" you should see a "Delete" button at bottom left. Tap, then tap cards to delete, then tap Delete again.
If you need more help with this, it might be good to email me so we can share pictures of what we are seeing.
Ernie
et@orangeorapple.com