Hrmmmm.. Never heard that question before and honestly never realized there wasn't an option to hide them.
The best way to do what you're looking for is to create a separate SCLogin instance for the employee area (which I'm assuming you already have). Then,
* In the Parameters -> Advanced area, set the "Module Class Suffix" to ' employee-login' (make sure there is a space at the beginning)
* Add the following to your template CSS:
.employee-login .sclogin-social-login {display: none; }
That should hide the login buttons like you're looking for.
I hope that helps, but let us know how it goes either way,
Alex