Vat Adding and Zero VAT

Hi Guys,

Its a simple question unfortunately I have searched but unable to find the answer.

My Question is:

I want to add VAT which I have already done with no issues but I also want to have the pop down menu so I can then select Zero VAT for when we export and dont have to charge for VAT.

Can anyone help please.

Further to this I have created the pop down menu but are unsure how to make it that if selected as Zero VAT it would remove the format cells that create the 20% UK VAT which already exists.