If you want to list the all the accounts username using SSH then run below command.
whmapi1 list_users
It will show list of all the accounts hosted on the server. It will show output like below:
[root@ ~]# whmapi1 list_users --- data: users: - abcded - dfgdfgdfg - dfgdfgdfg - rtytryrty - gfhjgfhj - fghfghfgh - iopuiopyuio - ghjkhjkhjk metadata: command: list_users reason: OK result: 1 version: 1 [root@ ~]#