BlackBerry Protect Anti-theft Protection
Downgrade from 10.3.2 to 10.3.1 - BlackBerry Forums at CrackBerry.com
See links in addition to post above.
If previous user didn't prepare device for new owner and you don't know BlackBerry ID, you are SOL.
Also, regardless, you likely wouldn't be able to downgrade, which is the minor issue all things considered.