Hi I my iPhone 11 Pro get random calendar events and it’s reported like virus so please help to delete it because it can’t delete from calendar

That is a Rogue Calendar account. 

If you are using iOS 13 then Go to Settings ➔ Passwords & Accounts and under Accounts see if an unknown calendar account is listed. If it is then tap on it and then Delete account.

If you are using iOS 14 the Go to Settings ➔ Calendar ➔ Accounts and under Accounts see if an unknown calendar account is listed. If it is then tap on it and then Delete account.

Note that it is not a virus. It is something that got added to your calendar because you may have accepted an offer from a pop-up on a website unknowingly. Please be careful out there.

Axel F.