Office 2013 shows those “Sign In” buttons everywhere. It’s kinda annoying, novice users may screw up and in a corporate environment it’s really not acceptable in most cases.
If you want to disable these items, your most convenient option is controlling it via Group Policy. Here’s how:
gpedit.mscand start it by pressing Return
That’s it. You may wanna run
gpupdate /force in a command prompt (
cmd.exe) for the changes to take effect, but you should be fine afterwards.