I accidentally did that
You accidentally tapped the lower left Edit button
Then you accidentally tapped the small red minus button next to your wallet.
Then you accidentally tapped the large DELETE button on the right side of your wallet (that appears only after tapping the red minus)
Then you accidentally tapped the red "Delete Wallet" button at the bottom of a warning message with red letters saying "If you delete your key you can not recover your funds."
1. You must be very prone to accidents.
2. That last warning screen says "Unless your Private Keys are safely stored elsewhere you will lose your Bitcoins!!" so I think the answer to your question is "You've lost your bitcoins."
I don't think there's some big secret, like "if you tap up up down down left right left right B A then it will undo all deletes" or something.
I am sorry for your loss. Perhaps something more like Coinbase would be better for you?