To edit or remove a user, go to Settings > Company Settings > Teams. Find the team member and click Option in their row. There you will have two options:
Change Permissions: This will allow you to change the access level this team member has.
Remove from Team: This will permanently remove this team member from the account, so they will no longer have access.
Now that you have your team all setup, you may want to organize these users into User Groups! Read more about User Groups here.