If you are a user The x and prefer to use a administrator account separately for troubleshooting or making various changes in system settings, most likely you want to hide that account (for security reasons) so that it is no longer displayed on Login screen in the system (or in the menu Fast User Switching). Also, user-ul you want to hide could be a user standard, necessary for certain tasks or a user Guest unused, etc.

How do we hide a user account on the Login screen in OS X?
Use: To use the following method of Hide on a user account in OS X, it is necessary to know the user's short name respectively (open System Preferences > Accounts, then click-right on the name of the user displayed in the list on the left and select Advanced Options; The short name of the user is the name written in law Account name).

- open Terminal (taste terminal in Spotlight) If you taste command sudo dscl . create /Users/ACCOUNTNAME IsHidden 1, where ACCOUNTNAME it is numele scurt al user-ului pe care doriti sa il ascundeti

- Then give restart system pentru ca setarea facuta sa aiba efect (dupa restart veti observa ca user-ul respectively nu va mai fi afisat in ecranele de login and logout FROM The x, in lista de avatare or in meniul Fast User Switching)

- in cazul in care ulterior veti dori sa reafisati user-ul ascuns in sistem, deschideti din nou Terminal If you taste command sudo dscl . create /Users/ACCOUNTNAME IsHidden 0

Note: Metoda descrisa mai sus pentru ascunderea unui user in OS X este compatibila doar cu OS X Yosemite (incepand cu versiunea 10.10); de asemenea, contul de utilizator ascuns folosind aceasta metoda poate fi accesat in continuare prin intermediul Remote Login, SSH sau Screen Shares.
STEALTH SETTINGS – How to hide an user account from the login screen in OS X