Realme
Change SIM PIN auf Realme
The SIM PIN is not tied to your Realme device. It is stored directly on the SIM card itself, which is why swapping the card into another phone still asks for the same code.
To change it, go to Tap on Settings ➤ Tap on Security ➤ Tap on SIM card lock. On a dual SIM device, you then need to Choose a SIM card (Dual SIM) before continuing.
From there, select Tap on Change SIM PIN and enter the current code when prompted: Enter the Current PIN and follow the instructions on screen. The new PIN takes effect immediately and is required the next time the SIM is inserted or the phone restarts.
Entering the wrong current PIN several times in a row locks the SIM card, not the phone. Unlocking it then requires a PUK code from your carrier rather than a factory reset.
If you only want to remove the PIN requirement entirely rather than change the code, that toggle sits in the same SIM card lock menu.