'To trim patterns and delete the empty space left by the deleted patterns, first create a loop cursor selection in the timeline around the patterns to delete, then long-press inside the loop area in the timeline. A confirmation popup will be displayed. When the sequencer is playing, a black line will show the current play position.' - Rej
Both myself and Britt have asked for this feature without realising that it was already there 
https://soundcloud.com/squirrelonmars
https://www.youtube.com/c/squirreIs
https://www.facebook.com/squirrelonmars
...and yup, just tested it and it still works in C3, long press to add measures, or create a loop point and then long press to delete measures.
https://soundcloud.com/james-muir
https://www.facebook.com/james.muir.77