Wug's toolkit can return you to stock (actually, all you should really need is the stock bootloader if you aren't still on it). You don't need to relock the bootloader to receive the OTA update however.
just read the post download imm76q and su file from step 4 place on sd card use cwm and flash the 2 files its really easy i did it last night if your stock rooted and unlocked you wont lose any info or settings
To receive OTA:
No system files may be modified.
No system files may be removed.
System files MAY be added.
I.E. if you're stock rooted you're fine...root just adds superuser as a system app.
Stock recovery, radios, and boot loader must all be in place.
Unlocked bootloader will still receive OTA.