You can remove people from the walk register if you have submitted it or not. When you submit a walk register you can go back and amend it for 48 hours.
To remove someone from the register go to the walk and click on Take register.
Choose View Register and remove the person by clicking on the orange box with a white cross by their name. You will be given the option to remove walker or indicate if they are the walk leader.
Once you have made your amendments, confirm the walk leader then submit the register.