How to delete an old address prompt

Give the following items a try to see if they can resolve this issue:

• Clear Safari browsing data: Open the Settings app on your iPhone, scroll down and tap on "Safari," then select Advanced > Website Data > Remove All Website Data. This action will remove any stored website data, including autofill suggestions.
• Reset location and privacy settings for Maps: Go to the Settings app, tap on "Privacy & Security," then select "Location Services." Scroll down and choose "Maps," and then tap on "Never" for the location access. Wait for a few seconds, and then change it back to "While Using the App" or "Ask Next Time." This action will refresh the location settings for Maps and may clear any cached data related to your old address.
• Reset keyboard dictionary: Open the Settings app, tap on "General," then select "Transfer or Reset iPhone." Choose "Reset," then choose "Reset Keyboard Dictionary" and enter your passcode if prompted. This step will remove any learned words and phrases, including autofill suggestions.
• Check contact details: Ensure that you have updated your address in your Contacts app correctly. Open the Contacts app, locate your own contact card, and verify that your new address is entered accurately.
• Restart your iPhone: Sometimes, a simple restart can resolve minor software glitches. Press and hold the power button (or the power button along with one of the volume buttons) until the "Slide to power off" slider appears. Slide it to turn off your iPhone, then press and hold the power button again until the Apple logo appears to restart your device.

After following these steps, test autofill in various apps to see if the old address prompt still appears. If it does, you may consider contacting Apple Support or visiting an Apple Store for further assistance.