Missing calender unsubscribe button at the bottom of calendar iOS 17.0.3

Hi DantiX,

Did you also try these steps from the Delete spam calendars and events on iPhone resource you're posting from?

"If this doesn't fix the issue, delete the calendar subscription in Settings:

1. Open the Settings app.
2. Tap Calendar > Accounts. Or if you use iOS 13, tap Passwords & Accounts > Accounts instead.
3. Tap Subscribed Calendars.
4. Look for a calendar that you don't recognize. Tap it, then tap Delete Account."

If so and you're unable to get rid of the calendar we'd recommend reaching out for support here: Get Support

Take care.