You can configure Space Settings to hide the space portal content, which is Announcement, Threads, Apps, People, and Related Apps & Spaces.

• The space portal content that can be hidden

Click the Options icon at the upper right of the space screen, then click Space Settings. Space Settings is displayed only for space administrators.

In the Contents in space portal page section on the Space Settings dialog, uncheck the check box for the content you want to hide.
The Contents in space portal page section can be configured only when Enable multiple threads is enabled.
Reference: Changing Space Settings