Spam calendar cannot be deleted

Hi to everybody out there,

got a problem with an old iPad (Gen. 4, iOS 10.3.3).

Description:

first appearance when we got some trash calendar messages: „take care, virus“, „activate McAfee“ and so on.

Checking this out, we found a new subscribed calendar we did not create called “Click ?? To Continue”

Solution approaches already executed until now:

1) usual „delete“-function to single entries does not exist for these special entries.

2) usual „delete“-function to whole calendar (Calendars/i (in circle), normally placed there in buttom, does not exist for this subscribed calendar.

3) Tip from German community: Go to Settings/Calendar/Calendars subscribed (ÍI am not sure, if “Calendars subscribed” is correct translation) to delete a subscribed calendar does not exist in menu.

I am a little disturbed to obviously compromised iOS.

Would be fine if anybody could help.

Thanks in advance

Thomas