Open Settings > Features (you need Manage features). Each feature is a switch:

Guides (Docs) are on unless you switch them off. Mail has its own set-up (see "Turn on Mail for your workspace (admins): short name, sender name, signature and rules").

Switching a feature off hides its pages from everyone, including people whose roles allow it. Nothing is deleted: switch it on again and it is all there.

Some features have their own settings under them: Moderation shows the Download module link, Recommendations lets you choose which ranks can be recommended, and Allowance sets the days per year.

Open Settings > Appearance & branding. Choose a Workspace Theme from the colours offered, or a custom colour. It is used for buttons and highlights, and you can change it any time.

Rosterr may show a seasonal look for a few weeks of the year (for example a Halloween theme from 15 October to 1 November). It appears if your workspace has the feature, you have not turned seasons off for the workspace ("Show seasonal themes in this workspace"), and you have not turned it off on your own device (in your appearance settings). Workspaces using white label default to seasonal themes off.

Your workspace already shows your group's name and logo. On the Business plan you can also switch on Remove Nebula Rosterr branding, which hides the Nebula name, mark, help button and chat. See "Business plan: your own domain, your own Discord bot and white label".

Home layout, banner and featured games are in Settings > General. See "The Home page: widgets, the sticky note and how admins arrange them".