Are you running RB V3.0 Beta?
If you are, there is now an option to turn this off.
Look in File > Preferences > RadarBox
and see if the 'Draw home Location Legend' is ticked
If it is ticked, check that you have the correct location set in decimal degrees in
File > Preferences > Home Station Data
Zoom out to make sure that it isn't showing but in the wrong position.
Lastly, check what colour you have set for 'Line of sight' in Map Colours, as this is also the colour of the Home Location marker.