You can delete your account from the “Setting” page within the Nuri Wallet app. You can also do so externally by sending a request to firstname.lastname@example.org via email from the same email address as the one linked to your wallet account.
Before deleting your account, withdraw all your funds to other cryptocurrency addresses you control. Please note that deleting your wallet account or app does not delete your wallet address or transactions stored on the blockchain. The blockchain records all transactions and keeps a permanent history that is always accessible.