Lock code needed to erase Iphone data About a week ago, I went to the Sprint store, and traded in my iPhone 6 for an iPhone 8.

They told me that they wouldn't erase the data on my existing phone for a few days in case I noticed that something didn't transfer correctly from the 6 to the 8.

Today, they called me and told me that they couldn't erase the data on the iPhone because they couldn't get past my lock code.  (For the record, I told them I'd swing buy and unlock it myself.)

This situation doesn't make sense to me because everything I've read suggests that it should be possible for a savvy user to erase data on a phone even if they don't know the lock code, and furthermore, I would have just naturally assume that a brick-and-mortar smart phone store would have the capability to erase a phone that had a lock code on it.  

Does their ask make sense?  Would a sprint store need a lock code to erase the data on a phone?
It is not necessary to be in possession of the lock code to erase the iPhone, since a DFU restore can be performed at any time (until iOS 12 restricts USB access after 1 hour since last unlock).

Activation Lock will remain if the device is still in your iCloud account's Find My iPhone, but it seems you've already removed it otherwise you could use the Erase iPhone feature remotely.