I believe I have maleware in my calendar on my iPad that would require a visit to Genius Bar at Apple store, but I am unable to find a way to communicate that. Not one of the choices.

If running iOS 13 or earlier versions, check: Settings - Passwords & Accounts - Accounts - Any rogue entries here? If so, delete the rogue account. 

If running iOS 14, check: Settings - Calendar - Accounts - Any rogue entries here? If so, delete the rogue account. 

The problem that you describe is very easy to resolve.

It is highly probable that an inadvertent click on a website link has “subscribed” an additional (unwanted) Calendar to your device - and this unexpected Calendar is exposing unwanted calendar events and sending you unexpected “adverts” or other warnings. 

You will need to check for what’s out of place...

iOS/iPadOS13 and earlier: Settings > Passwords and Accounts

iOS/iPadOS14: Settings > Calendar > Accounts

Look for an “account” that shouldn’t be in the list of accounts - as this will likely include the Calendar that contains all the unwanted events. When you find the suspect account, tap - then select Delete Account. This should resolve the problem in its entirety.

I hope you find this helpful in finding the source - and in resolving the issue if an unexpected Calendar is found.

You should not need to have a Genius look at it. Malware Calednars can be removed directly by you.

• On iOS, open Calendar. Tap Calendars >  > Delete the offending Calendar.