I checked in online for VIE-FRA-JFK. I've now decided that I would rather just ride the train to FRA, since I'm afraid VIE-FRA may not operate.

Can I check out online? I'm afraid I will be marked as a no-show for VIE-FRA and then lose my seat on FRA-JFK.

The ticket was originally booked with UA -- I can call them and delete the VIE-FRA segment, but they won't be able to touch the record since I'm already checked in for the flight.

Thanks.