It can be changed by using Terminal command:
sudo defaults write /Library/Preferences/com.apple.loginwindow SHOWOTHERUSERS_MANAGED -bool FALSE

revert back :
sudo defaults write /Library/Preferences/com.apple.loginwindow SHOWOTHERUSERS_MANAGED -bool TRUE

Sumber :
https://apple.stackexchange.com/questions/232449/remove-other-from-login-screen