The Administration Login/Toolbar is only visible when visiting your website at its Test URL (https://formedbywater.wavoto.com). The Test URL is only needed when building your website.
When your website is ready to go live, you'll want to register a personal website domain (e.g. http://www.mydomain.com) and use that instead. When you then share your website through email and social media posts, you'll always share with your personal domain. Your visitors will always visit your website at your personal domain and never see the Administration Login/Toolbar.
If you want to hide it now, simply log into your Back Office Administration, navigate to System > Settings, check option "Hide Admin Login Box" and save it.
One more thing: The "Log into Administration" link takes you to path "/Admin/". This path will always work with your Test URL and your personal domain.