It is simple to Delete a Group Member on WordGo.
Simply tap the 'Group Details' button (three connected circles icon) near the bottom left of your home screen. You will see a list of everyone in your group with an 'X' beside their names. If you tap the 'X' this will allow you to delete the Member from your Group.
Here's a video walking you through this process. If you have any further questions please raise a ticket here to contact a WordGo customer support agent.