How do I delete this update and go back to the new version it ruined my phone and can’t call anyone or text them

Sorry, but updates have always been a one way street. You can't go backwards.

Try a Forced Restart......Force restart iPhone - Apple Support

If no luck, contact your carrier to have them check the phone and text functions from their end.

You can’t revert a version, but you can troubleshoot the problem with your phone, which is NOT a defect in the update. Calling and texting are carrier services, so contact your carrier to resolve the problem. Your iPhone 6S should be updated to iOS 15.8.