Can you get rid of the new update 17.3 once you've installed it? How do you do that?

Since downgrading is not possible, maybe describe the issues that you are having. While features were added like Stolen Device Protection and Music collaboration, there were very little changes to the UI from the last 17.2 point release. Those are features that you don't need to use and won't interfere with the normal workflow of using the phone.

Can you get rid of the new update 17.3 once you've installed it?

No

iOS updates generally aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. "Screwing Up" issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors.

See what each update does: About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...