my calendar has had hacked how can i remove them please

You aren't hacked, but you may have inadvertently subscribed to a spam calendar from the web.

To remove the calendars, tap Calendar in the bottom, then the more info button > then Delete Calendar. If the spam continues, go to Settings > Apps > Calendar > Calendar Accounts > Subscribed Calendars > Delete any unknown accounts. Those spam accounts would be the ones sending the junk calendars out.

As for the other spam, the invites, tap on it then Delete and Report Junk. Then clear out your spam/junk email and messages as that is where the invite suggestions come from.