The official format is REGEDIT4. Exported regs in "Windows Registry Editor Version 5.00" format will work too, but the rgu file itself must have REGEDIT4 at the top.
To remove an entire key (folder) you can use..
Code:
[-HKEY_LOCAL_MACHINE\SomePath\ToTheRegKey]
To remove a single entry, no matter if it's dword or string..
Code:
[HKEY_LOCAL_MACHINE\SomePath\ToTheRegKey]
"EntryToDelete"=-