Why did my contacts re-populate on iPhone after deleting it on iCloud?

Hi PopeyesFriedChicken,

It sounds like you're looking to ensure contact synced with iCloud are removed from your iPhone. If so, check out the information below found in the article here first: If your iCloud Contacts, Calendars, or Reminders won’t sync - Apple Support

"Things to check first

1. Check the system status of iCloud Contacts, Calendars, or Reminders for services outages or connection issues.
2. If a reminder isn't showing up on some of your devices, make sure that your iPhone and iPad have the latest version of iOS or iPadOS, or that your Mac has the latest version of macOS.
3. Make sure that you're signed in to iCloud with the same Apple ID on all of your devices. Then, check that you turned on Contacts, Calendars, and Reminders in your iCloud settings.
4. Check that the date and time settings on your device are correct for your current location. 
5. If you use iCloud for Windows to sync your Contacts and Calendar with Outlook on your PC, make sure that you've updated to the latest version of Windows. Then follow these steps to sign out and sign back in again. "

If your settings are correct, check your iPhone to see if you have a third-party account synced with that contact data. The article here has steps to help you check which accounts are synced: Manage and delete contacts on your iPhone or iPad - Apple Support

Also, a normal restart of your iPhone may help to sync the data. Find those steps here if needed: Restart your iPhone - Apple Support

Cheers.