Root unrooting help

[xwikedonex]

trying to unroot to stock, i got the phone from my brother. it has super user on it. i tried using root explorer to delete the su file as described in one tutorial. couldnt find the su file in the bin folder so i couldnt go tothe next step. tried super one click, either always "waiting for device" or one time it connected but failed to unroot. any ideas on what i can do now?
thanks

 

[xwikedonex]

i was able to get into the phone and delete super user. used root checker and it says the phone is not rooted. however after i activated the phone, it will not accept the vzw update. it fails every time. does this mean that there is still rooting problems?