The first time you used Google maps your browser would have asked if you were happy to share your location with Google.
If you clicked 'yes' you gave Google permission to use your browser's geolocation feature to work out where you are. If that sounds like your situation you can turn the facility off. The way you do it depends on which browser you use, so look in the settings options.
Google can track you via your mobile phone, as already indicated, and there is a PC version of the software that enables them to do it, but you have to opt in for that to happen, and you've already said you didn't do that.
You can be tracked via wireless hot spots too, if you use them, but that's normally going to happen when you're using a laptop or tablet.
If you haven't enabled the tracking option in your browser for Google maps I'm at a loss to explain the reason it's happening.