How to remove demo/retailer mode on Samsung A52 5G

There was no open for the device Samsung A52 G so I just put A51 as the closest to it, anyways got a phone off eBay because I was recently mugged and need a phone for most of my school work and I’m tight on money so I got the cheapest off eBay until I make enough for a new one and the demo/retail mode is still on. I thought I would be able to get rid of demo mode on Samsung just like I did with an Apple iPhone before but Samsung is harder to bypass on removing the demo mode. I have tried many methods and 1 is by going to the settings to reset and factory reset there but it’s grayed out and I can’t tap on it. 2 I did a hard reset doing the volume up/power button to factory reset but nothing happened, the phone still turns on normally without showing the factory reset page as it did on the videos I watched. 3 I made a Samsung account to go into the find my device phone on the demo phone to erase data but it opens a new website saying “500 error UNAUTHORIZED EXTERNAL”. I’m stuck on what my options are and I don’t want to waste money on some app that will most likely not even help in removing the demo cause I’m tight on money and need this device for my school work at the moment TIA

I was able to disable demo mode