Any member of your club can be configured to have admin access, there are no restrictions on the number of administrators. This means there is no one admin contact, however often the reality for smaller clubs is the responsibility falls on one person.
Should you wish to give a new member administrative access, go in to Club Database > Members > Manage members, and edit their member record. To give them access to make changes to the website you need to amend the details shown under the Website access setting.
It is also important to ensure that the main billing contact details are updated. To amend the billing contact email held for the club, go to Billing > Billing Contact