There are two steps which must be followed in order to show the products’ prices without the tax.

First, open the Joomla administrator area->Components->VirtueMart->Admin-> Configuration->Globaltab. Make sure that the Show “(including XX% tax)” when applicable? option is not checked.

Then navigate to the Joomla administrator area->Components->VirtueMart->Shopper-> List Shopper Groups. Click on the shopper group(s) which you are using and deselect Show Prices including tax? check box.