The Google TOS says, applicable to creation of accounts:
You may create your own Google Account, or your Google Account may be
assigned to you by an administrator, such as your employer or
educational institution. If you are using a Google Account assigned to
you by an administrator, different or additional terms may apply and
your administrator may be able to access or disable your account. To
protect your Google Account, keep your password confidential. You are
responsible for the activity that happens on or through your Google
So the account wasn't created for you by an administrator, and it is your own Google account. The terms say that you are responsible for what happens with your account, thus if you were to turn over the password to someone else and they did illegal things, you would be responsible (at least with respect to your legal relationship to Google).
Google does have business email, which your employer apparently did not utilize. In order to have actual ownership of the account, the business would need to set up the account for you and claim initial "ownership". If you create an account for the convenience of a business, that convenience – but not the account – is a gift from you to the business.