Hey, @JAlle-1189!
All you have to do for this is go into the Assets part of the app (click the three horizontal lines in the upper-left) and then add or remove shipments from there.
Here's a ~2-minute video I created on managing shipments (and everything else on the Assets page):
Managing Vehicles, Trailers, and Shipments in Geotab Drive
Hope this helps! :)
Best,