No, you dont have to power off. SIM cards can be removed at any time.
Can you remove SIM while phone is on?
You can remove the sim card while it is on, but the phone will just ask you to reboot anyway. You can switch it to flight mode and then take out your sim card, swap it and then turn off flight mode.
Do I need to remove the SIM card from my old phone?
Although some smartphones may have a SIM, its either because it is needed to connect to the 4G LTE network, or to allow the phones to function in foreign countries. When you cancel your service or activate a new phone your old SIM should automatically be deactivated, making it a useless piece of plastic.
Should I turn off Iphone before removing SIM card?
It is possible to remove the SIM card without turning the phone off. However, manufacturers, including Apple, warn of a possibility that static electricity could damage the card or the device itself.
Can I remove SIM while iPhone is on?
Dont attempt to remove the SIM card while the device is powered on. Doing so may harm the SIM card and/or the device. Ensure that the device is powered off. From the right edge of the device, remove the SIM card tray.