Can I turn maps off to reduce data usage?

Yes. From Settings (gear icon), go to Maps and Tracks and turn Map Data off.

 

Note: Turning Map Data Off, does not turn off map data for the Apple map types (iOS 6) or the Google map types (iOS 5).  This feature is incompatible with the iOS Map Kit and therefore does not disable Apple or Google map tiles from being downloading when Map Data is turned off.