Team management in GitHub’s organization is very simple, but the UI is hard to find.
First of all, you need to join an organization first, this is the basic assumption of this post.
Then click the icon in the most top-right corner, Your Dashboard. Sadly there is no text(even hint text when hovering this icon) explaining it, so previously I found nowhere to manage a team.
After this, everything becomes quite straight-forward.
Switch your account to the organization(NetEase, in this example), then click Teams button.
Now you should be able to see the teams you’ve joined, and the privileges gained.
If you want to edit team members, click the team(Emmagee for example) link and do what you want.