Error "cannot verify server identity, the identity of "levelofmye.biz"

Go to Settings > Calendar > Accounts and delete the calendar subscriptions that you do not recognize.

If you don't see any subscription or suspicious account:

• Open the Calendar app.
• At the bottom of the screen, tap Calendars.
• Look for a calendar that you do not recognize. Tap the More Information button “i" next to this calendar, then scroll down and tap Delete Calendar.