I'm not sure if you're referring to the actual ticks or to the associated tick text. I'm assuming that you want to remove the associated tick text. I would modify the associated css in order to get the effect that you want.
Assuming you've created your svg component that you wish to draw, create a group and give the group the class labels of y and axis. This will give you refined control over both axes.
// Add the yAxis to the graph
svg.append("g")
.attr("class","y axis")
.attr("transform", "translate(" + margin.left + ", 0 )")
.call(yAxis);
Associated CSS
.y.axis text{
display:none;
}
Check out this fiddle to see an example: