You can remove the VAT on product lines in the invoice editor under Invoicing settings -> Visible columns:
In this case, the VAT column will disappear, but you will still see Total VAT and Net Total at the bottom of your bill:
To remove all mention of VAT (e.g. Net total) from your invoice, you can set the invoice type to ‘Sales exempt from VAT’:
Please note, that even if your company is not VAT registered, it doesn’t automatically mean that your sales are exempt from VAT. This is why we highly recommend checking this with your accountant. You can also read more here.