Locking and reunlocking did not work, but it triggered a thought.
I went to app settings and Force Stopped the app and then reopened it. It then took me to the main screen where it shows payment cards, rewards cards, offers and transactions.
From here I was able to see Settings then Reset Google Wallet.
Update. There is no need to click force stop...just click the words google wallet at.the top left and it will take you to the main screen. You can then choose menu, settings and then reset google wallet.