The short answer is NO, you cannot change a Google Account from Business to Personal. The good news is that the distinction you are making doesn't really make sense in this context so you can keep the existing Gmail address. Do not shutdown the Google Account.
The problem is the Google My Business Profile not the Google Account.
First I would encourage you to familiarize yourself more with the ins and outs of the My Business Profile prior to deciding how to proceed. Note that it is difficult to search this topic without being inundated with results from marketing and SEO-related businesses trying to sell you their assistance. I did include some Google support explanations in the Resources section below to help you get a handle on the monster that just ate you for lunch.
How you got here
Google encouraged you to do a number of additional things when you indicated that the new Google Account was for a business. All of which are always available to any Google Account holder. The difference being that Google fast-tracked their setup based on your responses indicating that you managed a business.
What you now have
- A Google Account with your typical free Gmail address.
- A Business Profile which you were guided to setup.
- Any related features which you configured (e.g. Map listing, etc.)
Business Profile isn't Google Account
The Google Account (Account) and the Business Profile (Profile), while they may look intertwined, are separate.
The thing that ties them together is the fact that your Account has been verified to act in the Primary Owner role for that particular Profile.
- You could add additional Accounts to help you manage the Profile (Owner role and/or Manager role).
- You could transfer ownership of the Profile to another Account and cut off your own ability to access it.
- you could also delete (Remove) the Profile (see below)
Understanding Profile Ownership
This link is to a Google support page regarding transferring a Business Profile and it includes great resources to help understand the relationship between your Account and the Profile.
You cannot remove Q&A unless you remove the Profile. Please note that Google will still solicit information about your business through questions to Mobile users (Local Guides) as well as Reviews.
Your Business may show in Maps regardless whether you remove the Profile or not. The advantage of a Profile may be the ability to control what that address is (alternate address etc.). There are a small number of what Google considers Ineligible Businesses but outside of those if they can tie a business to an address they will. (See the Remove a business from Maps section of this link). They will correct address errors.
Remove a Profile
You can Remove a Profile however it may not have effect you intend.
If you remove the Profile what you are doing is cutting off your Account's verified ownership of the business associated with the Profile, and your Account's ability to manage the information.
Much of the public facing information will still remain. For example, if you didn't create the Profile at all, but your business simply left a footprint on the Internet (merely by existing), Google would return any information it could about your business, anytime it was inclined, to the Public.
If you Remove your Profile, you can take Ownership of it again in the future by going through a verification process.
Business Profile FAQs:
How Google sources & uses info in Business Profiles & local search results:
Remove one or more Business Profiles from your account:
Transfer primary ownership of a Business Profile
Includes: Understand profile owner & manager roles):