I keep getting a pop up that request the Administrators name and password. I never set this up so I can't bypass this. How do I change or set up the administrators name and password.

Question

I have OS X version 10.9.5.   I have had this for a year or two.   How do I find my Administrators name and password?  I do not recall ever setting this up.  

Answer 1

If you don't recall setting it up, try entering nothing into the passwordfield and just press return.
If that worked, please go to " > System Preferences > Users & groups" and click the [change password]-button.
If all that doesn't solve it, boot from the Recovery Partition and reset your password from there.
Here’s how:
1/ Make sure your computer is completely shut down.
2/ You’ll have to be quick next: Press the Mac’s power button. As soon as you either hear the loud chime, or see the display light up - usually after a second or 2 - on your keyboard press [cmd] + [r] Keep these keys on your keyboard pressed until you either see an Apple Logo with a loading bar or a spinning gear.
After a few minutes, you’ll be presented with a Utilities screen. This is the Recovery partition. If this step is already giving you problems, try using a USB-keyboard. It doesn’t have to be an Apple-keyboard. If you have a Windows-tailored keyboard laying around, use the “Windows-flag” key in stead of the [cmd]-key and it should also work.
3/ Find the menu called “utilities” in the top left corner of your computer’s display. It’s in between the menus “edit” and “window” Don’t be confused with the menu called “os x utilities” 
Choose Terminal. A somewhat old-fashioned looking window will pop up, waiting for a text command from you. This is the Terminal.
After the # type: resetpassword and press return. Note that there is no space between ‘reset’ and ‘password’ 
What you’ll see next is an rectangular window that gives you the option to reset passwords. Set a new password for all the users that you need.
We’re ready to reboot your Mac now. Click on the Apple Menu and choose “startup disk” Choose to boot from “Macintosh HD” Please let us know if this solved your issue, or if the steps above did not work, or could not be performed for some reason.