Magento provides a configuration option to help you show a demo store notice when your web store is not yet live and you are just running a demo store.
To enable/disable the demo store notice:
1. Log into the Magento Admin
2. Navigate to System >> Configuration
3. Select the Design Section
4. Click to expand the HTML Head block group
5. Select “Yes/No” from the dropdown for “Display Demo Store Notice” to “Show/Hide” the demo store notice. You will find this dropdown at the end of the HTML Head block group.
6. Click the “Save Config” button to save the configuration changes.