Setting a Space's Allowed Content Types

You can set which content types a space supports, for example, discussions, videos, ideas, and so on.

Fastpath: Admin Console > Spaces > Settings > Space Settings
Spaces can support a variety of content types, which you can configure. For example, by clearing the Documents check box, you'll remove the Create > Document link from the space's Actions list. In addition, users won't be able to select that space from the place picker before posting a new document.
If users have created documents in the space already, and then you clear the Documents check box to remove support for them, existing documents will no longer be viewable in the space (although they'll still exist).