My Calendar showing that my iPhone is being hacked and not secure

SCAM! Check these link...

Delete spam calendars and events on iPhone - Apple Support

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Why do you think you need a calendar?

From the articles linked above.

How to remove calendar spam on your iPhone

1. Open the Calendar app.
2. At the bottom of the screen, tap Calendars.
3. Look for a calendar that you don't recognize. Tap the More Info button  next to that calendar, then scroll down and tap Delete Calendar.

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.

It is a scam. Delete the entry and ignore it.

arthit272 wrote:

How do I delete it .... so I just delete the calendar app

No, deleting the calendar app will not help. Check the links from frazzm737 above.

You are welcome.

Assuming you have already removed the spam calendar entries, Yes.