Yes. Basic Plans can only have one Admin. The current administrator can transfer rights to a different user at any time. To do this, go to your Account Settings page, make sure it's on the Subscription tab and then select “Change” next to your name. From that dialogue, you can choose the new plan admin.
If your previous admin has left the company, or you need further assistance, you can contact support (firstname.lastname@example.org) for help as well. Just let us know who needs to be the new admin, and we can make the change for you.
Professional or Enterprise Plans are able to have multiple Admins on the account. Find more information on adding multiple Admins on a Professional or Enterprise Account here.