[stroths]

Compliments of XDA

Restore/Remove clock on top bar

[HKLM\Software\Microsoft\Shell\]
"ShowTitleBarClock"=1 (enable)
"ShowTitleBarClock"=0 (disable)

Show Time,Date,both or Battery on top bar at Today screen

[HKLM\Software\Microsoft\Shell\]
Time:
"ShowTitleBarClock"=1 / "TBOpt"=1
Date:
"ShowTitleBarClock"=1 / "TBOpt"=2
Both:
"ShowTitleBarClock"=1 / "TBOpt"=3
Nothing:
"ShowTitleBarClock"=1 / "TBOpt"=0
Battery:
"ShowTitleBarClock"=0 / "TBOpt"=1

You may have to add TBOpt dword value if it doesn't exist. These settings won't take effect until a soft reset.