When you create your company account in Get on Board, the person who created it will automatically be assigned the role of admin. This person will be able to manage member invitations to your account, and assign admin roles to other collaborators (among other permissions).
If you have an admin role and want to reassign roles, go to Users and Groups where you can find the list of users who have access to your company account. With just 1 click you will be able to change the role of each team member of your company. You can assign them other roles, remove them or revoke access.