What is "Other" account on OS X Yosemite login screen?

I am using OS X Yosemite. I am seeing 2 accounts on my login screen. One is my account and the other has the name "Other". What account is that? When I click on it, there is no username. When I try to shut down my computer, I am now prompted to enter my username and password. Previously there is no need to do so. I have tried the suggestion here How to get rid of the "Other..."-Account on the login screen? but that only hides the "Other" account. I am still prompted for my username and password when I want to shutdown. How do I remove/disable the "Other" account, not just merely hides it? Thank you for the assistance.