Removes the wallet encryption key from memory, locking the wallet. After calling this, you will need to call walletpassphrase again before being able to use private keys.
curl --user myuser --data-binary '{"jsonrpc":"1.0","id":"1","method":"walletlock","params":[]}' -H 'content-type:text/plain;' http://127.0.0.1:8332/null