I don't think that what you are asking is possible.
When a handgun gets entered into NCIC as stolen, it stays there until someone with access at the original entering agency cancels it out. Someone at the recovering agency can enter it as "recovered," however.
Either way, it would be possible to trace back who canceled the entry (or entered it as recovered) to a specific user. So if someone DID "make the entry disappear," they would quickly be caught.
-Citicop.
Sometimes there's Justice...
and sometimes, there's Just Us
1*
In memory of DCLaw- EOW@RealPolice 02-20-2007.
We won't rest 'till we find the mutt.