If you are embedding Rocket.Chat in your site, you can change Rocket.Chat's layout by adding
?layout=embeddedafter your server URL.
Adding this to the URL will change the layout of Rocket.Chat to a more "simplistic" view, hiding the left sidebar with the channel lists and account management buttons. Additionally, you can enable the top navbar in the embedded layout by going to "Administration -> Layout -> Interface -> Show top navbar in embedded layout".
Setting a URL to embedded mode will "lock" that view in a single channel (since the user will not have access to the channel lists).