dodo,
As of now the margins for the plot area are automatically calculated and can’t be customized. For removing the extra margin from the bottom and left you can set axisX margin and axisY margin to -10 as shown below:
axisX: {
margin: -10
},
axisY: {
margin: -10
}
Please take a look at this JSFiddle for a working example with sample code.

__
Anjali
Team CanvasJS