Protect GitHub Branch

• Open GitHub
• Select Repository for which protection is to be defined.
• Select Settings
• Select Branches
• In Protected Branches, select a branch to which protection is to be defined.

• Check "Protect this branch", which helps to define protection policy for the branch
• Require pull request review before merging 
• Restrict the list of user can merge the changes 
• Require status check, this can help to check status from external service before merge.

• Enterprise edition Protection options

• Open Source edition Protection options