How do I disable retail mode?

In most cases, the demo phones use a specific ROM that Samsung does not use on normal retail phones me and you normally purchase. These demo phones typically need to be reflashed with the retail ROM or it will always be present on the phone, albeit neutralized. Since you have one of these, check if it has an IMEI. The Galaxy S demo phones which were not intended for resale lack this, so while it’s less likely on a cheaper phone like this where the store will probably just load the demo app on it instead of getting a demo-specific version, you need to double check while you can return it.

If the phone has the normal Retail ROM that isn’t specific to demo phones, the app can be removed with a factory reset or disabled in the developer options. On the demo ROM, the phone is a brick sad to say. You can only disable it on retail phones. I don’t know about the viability of flashing a normal ROM to these phones (it likely has a different signature and probably uses the KNOX boot signature enforcement the US carriers love) so you may be stuck with it on this one. Samsung also does not support bootloader unlocks unless you have an EU Exynos phone because of the US carriers.

I’m going to mirror @mayer here to a certain extent. The codes are available if you look online (but may not work) and can be found if you have to as a last resort, but I’m not going to link them because the risk of being an accessory is too great. Try to go to the store you purchased it from and get them to deal with it first and don’t let them say no and push you away; they should have disabled this before you left the store.

Factory reset your phone, when reset go to about phone in settings, and allow developers mode by tapping the build version several times until enabled , then enter developers settings , look for the demonstration setting and turn it off,.

I have not tried this but have seen it in the developers options . Hope it works for you.

How to find retail mode password missing

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