I think, IIRC, the “Find my iPhone/iPad” feature cannot be disabled (even on devices that aren’t password protected) unless one enters one’s Apple ID and password. I had to do this multiple times when I had to reset my iPhone multiple times due to an unrelated issue (iTunes won’t let you “restore to factory defaults” unless you disable “Find my iPhone).
Maybe this has changed (but that would be a step backwards in terms of security) or maybe one can change the settings for Find my iPhone so that one doesn’t have to enter an Apple ID and password. I don’t know.
First, on the “Find Your iPhone” ... you do have to activate it first, before it’s going to protect your iPhone or iPad. If you don’t activate it, it’s not going to protect your device.
THEN ... once it’s activated ... it does require your Apple ID and Password to deactivate it, when the device gets “locked up” (as in when someone steals it).
The device will be a “permanent brick” and useless if you don’t enter your Apple ID and password (or if you forget it). There is no recovery from this if you forget it. Your device is permanently useless after that!
Apple will NOT ever unlock it for you, unless you actually prove you bought it from Apple or an Apple authorized seller. If you bought it from a neighbor or a relative, Apple will NEVER unlock it for you. The device is permanently useless after that!