Is it possible not to show gst on sales invoices? if so how to go about in quick books?

That's possible, bwaghela. 

You can uncheck Tax in your invoice template content and it won't show up in your email invoices. 

Here's how: 

1. Go to the Gear icon and then select Custom Form Styles. 
2. Click the template that you are using. 
3. Select the Content tab and click the Table section. 
4. Uncheck the Tax box and then click Done. 

If you are referring to the GST column in the Invoice window, it can't be removed. 

You can always post again or drop your comment below if you have additional questions.