Disable tick marks on Secondary Vertical Axis
We are looking for a way to remove the tick marks for secondary vertical axis, unfortunately there is no such option within the Overlay Chart, however this is possible for removing via the main chart.
As you can see in the below image you can see the tick marks are by default turned on:
Below you can see what options we have for;
Looking at the Style options we do not have the Show Tick Marks available.