Organization owners can set team creation permissions.
If you do not set team creation permissions, all organization members will be able to create teams by default.
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In the upper-right corner of GitHub Enterprise Server, select your profile photo, then click Your organizations.  
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Next to the organization, click Settings. 
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In the "Access" section of the sidebar, click Member privileges. 
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Under "Team creation rules", select or deselect Allow members to create teams. 
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Click Save.