As with all street maps, occasionally the information shown may be outdated or incorrect. The street maps overlaid on Nearmap imagery in the new MapBrowser are provided by Google™; Nearmap has no ability to edit them.
The easiest way to correct the map is to find the location of interest in Google Maps and click Send Feedback at the bottom of the window as shown below. Then just follow the instructions provided.
Google also provides a convenient interface that allows you to submit any requests for more complex modifications that you have: Google MapMaker.
To use either approach, you'll need to log in with a Google account to submit change requests.
The StreetView™ tool can be very useful for verifying addresses by looking at the numbers on buildings.