Step-by-step instructions
Log In to your google account & search your business in the Google search tab.
Alternatively directly Sign in to your Google Business Profile.
Now you will see "3 dots" adjacent to "Your business on google". Click on those 3 dots.
Following that, click on "Business Profile settings".
Under the Business Profile Settings, you will get an option to "Add, edit or remove people's access" click on that.
Now click on the "Add" button to enter the email ID of the person you wish to grant access to.
Enter the "email ID" & select the one from the prompted options.
Now the final step is to choose an access level: "Owner" or "Manager" & click on the "Invite" button.
The Invitation sent by you will appear in the pending list till it is accepted by Invitee.