Hi there! I understand you're having trouble with the USPS app on your iPhone running iOS 18.2.1—specifically, you're unable to delete completed tracking numbers and can't add new tracking numbers. Let's see what we can do to fix that.

First, could you tell me if you’re using the latest version of the USPS app? Sometimes app issues happen when the app isn’t up to date.

Meanwhile, here’s a step-by-step approach to try:

1. Restart the app: Completely close the USPS app (swipe it away from the app switcher) and then reopen it. This can refresh its state.

2. Check internet connection: Make sure your iPhone has a stable Wi-Fi or cellular connection. Sometimes poor connectivity can cause these issues.

3. Update the app: Go to the App Store, check for updates of the USPS app, and install the latest version if available. Older versions might have bugs causing your problem.

4. Clear app cache (if available): Although iOS apps don’t have a clear cache button, you can uninstall the USPS app and reinstall it; this often resolves glitches like stuck tracking numbers or adding new ones.

5. Sign out and back in: If the app requires login, try signing out of your USPS account in the app and then sign back in.

If you’ve tried these and still can’t delete or add tracking numbers, the issue might be on USPS’s end, as other users have reported similar problems recently with the app’s tracking management functions1.

Please try these steps and let me know how it goes, or if you’ve already tried any of them. We can then explore more advanced solutions or figure out if the issue needs to be escalated.

Are you able to check the app version and start with these steps?