After logging in to Google MyBusiness here, the owner of a Google My Business listing can invite additional users to own or manage a business listing. Adding owners and managers lets users share management of a listing without having to share personal account information. Owners, managers, and communications managers all have different levels of access to the listing.
Only an owner can add or remove users. However, a manager may remove himself or herself from a listing. Google Groups can’t be added as managers or owners of listings.
You can find written instructions on the process here on Google’s support site. Or just watch the short video below.