How do I remove the SIM card

See the following Apple Support article for information on removing a SIM card, including the excerpt below: Remove or switch the SIM card in your iPhone - Apple Support

Find your model below to locate the SIM tray. To pop open the SIM tray, insert a paper clip or a SIM-eject tool into the hole beside the tray. Push in, towards your iPhone, but don’t force it. If you're having difficulty ejecting the SIM tray, take your device to your carrier or an Apple Store for help.

and

Find the SIM tray on the right side:

• iPhone SE (1st, 2nd, and 3rd generation)
• iPhone 8 Plus
• iPhone 8
• iPhone 7 Plus
• iPhone 7
• iPhone 6s Plus
• iPhone 6s
• iPhone 6 Plus
• iPhone 6
• iPhone 5s
• iPhone 5c
• iPhone 5
• iPhone 4s
• iPhone 4 (GSM model)