If you are using the Google Play Store to play, then you will need to contact their support team. If you are playing on iOS, then you can reset your account by following these steps:Log out of the game and delete it from your device.Reinstall the game and log in with your old account information.Verify your email address.
Go to the home screen of your Nintendo SwitchOpen the eShop and search for “Gems of War”Click on “Gems of War” and buy the gameExit the shop and go to your home menu
To delete your account, you will need to contact a customer support representative.