You may configure EasySocial to allow users to change their username by editing the options of the Joomla Username field in EasySocial. To enable this, first access the Profiles area at the back end of EasySocial. Then, click on the profile type which you would like to configure.
Upon viewing the profile type's information, click on the custom field tab. After that, click on the Joomla Username field and you would see a screen that looks similar to the following:
To configure this, proceed to the Settings section at the back end of EasySocial and click on the Users settings. On this page, scroll down to the bottom until you see the screen below:
For the option Allow change on edit, ensure that this option is enabled and users will be allowed to change their username when they edit their profile.