To remove the SIM card from your iPhone, you'll need to eject the SIM card tray with a special tool or paperclip.
If you need to find out your iPhone's carrier without a SIM card installed, you can do so through the Settings app.
Apple continues to phase out the physical SIM card tray on iPhones, with the latest models relying solely on eSIM technology in more countries.
The iPhone Air will only have an eSim - will other phone makers also shift away from the familiar - but fiddly - plastic ...