Yes you can do this. It is all controlled from the window you are using in your project. First the window must have been created when WebHelp was your default Single Source Layout. If it isn't, right click on WebHelp in the Single Source Layout pod and select the Set as Primary Layout option. To create a window, open the Project Set-up pod, right click on the Windows folder and select New Window. If you already have a window, double click on it to display its properties. On the right hand side you'll see a series of tick boxes in the Buttons section. You just need to deselect the Contents tick box. Note that this is the default button be default so deleting it will mean you'll want to assign one of the others as the default. To do that, select the button and click the Set as Default button.
I hate to disagree, but I think Colum is leading you down a dark alley.
Unless I'm horribly mistaken, you accomplish this by adjusting a setting in your Single Source Layout recipe. I know you said you are using TCS, but you didn't say which version. So I'm going to assume version 9 here.
From the Single Source Layouts pod, double-click the WebHelp layout. Then click the Navigation section and clear the TOC check box to remove the TOC and the TOC button in the skin.
Click the image below for larger and clearer view.
Once you have done this, generate your WebHelp again.
Helpful and Handy Links