Really easy to do but business must be added to Google first: In UK the link is https://www.google.co.uk/business/
Probably something similar for your location. Once added and verified you can move map pin to exactly where you want it.
I have dozens in my google account for clients and it really is simple to do.
this page might help but definitely better through My Business section as you do not have to prove ownership.
https://support.google.com/mapmaker/answer/6296952
Mandarin, thank for the tips... that worked! I had to have Google mail my client a postcard with a Verification Code which they received in a couple days. My client then sent me that code and when I entered that, it allowed me to move/save the location pin on Google Maps.