Yes, you can remove your employee if they no longer need GoCorp access by deleting them from the list. You need to access "Employee & groups" menu on the sidebar and follow these simple steps: 
1. To remove GoCorp access, you can tick the checkbox next to the employee's name and hit the delete button (top right) 
2. You'll get the confirmation screen - click "Yes, remove" if you want to deboard that employee 
3. Once an employee is deboarded, he/she won't have access to GoCorp anymore 

*Note: the completed trips by that employee will still appear under the trips section.*