Yes, you can. The flow depends on your device.


On the flight feed cancel the Check-in. 

Then tap on the "Cancelled" word.

Go through all the screens till the screen with passengers. Tap on the passenger you want to edit. 

Edit info and tap Done / Next. Then submit check-in again. 


On the Flight Feed cancel the Check-in.

Tap Check-in

Select the passenger which you want to edit.

Correct info and save it by going "Next". Submit check-in.