I Am Running Ppe Tech Iv Programmer. This Programmer, Once Installed Can't Be Removed. If For What Ever Reason I Wanted A New Programmer, Would It Over Write What Is Currently In There. The Saleman At Ppe Said That The Dealership Can't Erase What's Stored, So I Don't Have To Be Worried If I Needed A Reflash.
Don't Get Me Wrong I Am Happy With My Stack, It Works Well, But Just In Case.

You should buy a second PCM with a stock flash on it for dealer visits.

So The Saleman Lied, And The Dealership Can Erase My Program?

Dunno. You can "lock" custom tunes so that they cannot be erased. Not sure if that's the case.

If the PCM is locked, and you go to a dealer, they can probably find out that it has an aftermarket tune in it. But that is true even if the PCM is not locked and you have a tune in it.

Steve Cole (Diesel Tech) might be able to give you more insight into it.

if its a tech4, the only one who can update it is Diesel Tech.

If is has the 3-way selectable tunes, then what DP mentions above. If it has a single tune, then I believe the dealer will be able to re-flash the ECM, but then you loose the performance program.