[GW: You will have to click the lock icon because you need to un-gray the Enable Root User menu selection. The instructions below also enable you to *change* the root user. This is good for OS X Mavericks (10.10) and earlier. There is a simpler way to do this for 10.11 and later.]

Enable or disable the root user

Choose Apple menu () > System Preferences, then click Users & Groups (or Accounts).
Click lock icon, then enter an administrator name and password.
Click Login Options.
Click Join (or Edit).
Click Open Directory Utility.
Click lock icon in the Directory Utility window, then enter an administrator name and password.
From the menu bar in Directory Utility:
Choose Edit > Enable Root User, then enter the password that you want to use for the root user.
Or choose Edit > Disable Root User.

the standard unix password manager

Password management should be simple and follow Unix philosophy. With pass, each password lives inside of a gpg encrypted file whose filename is the title of the website or resource that requires the password. These encrypted files may be organized into meaningful folder hierarchies, copied from computer to computer, and, in general, manipulated using standard command line file management utilities.