There is no such settings in EasySocial. The only settings available is to choose between username / real name.

The reason that the e-mail is being used is most likely because you have configured EasySocial to use e-mail as username. You can change this behavior under Settings > Users > Authentication

Can this be changed by the admin ?

Hi Danny,

Yes. Only "super user/administrator" can set those setting at Backend>Components>EasySocial>Settings>Users>Authentication as shown http://prntscr.com/by0nsr.