Remove tax being calculated on shipping from draft order

[Hoeky21]

Hello all!
Thanks for taking the time to read my problem!

I have this app installed called " Wholesale Pricing Discount" to make draft wholesale orders. The issue arrises when I'm trying to add my custom shipping rate to the draft order and my Shopify store is charging my provinces tax @ 13%. Because I have already received a shipping quote from my shipping company I don't need to apply any more tax. I've already went into Shopify -> Settings -> Taxes and Duties -> unchecked Charge Taxes On Shipping Rates.

The draft order page is still charging tax on my custom shipping cost I put in. Any suggestions? 

Thanks,

Rebeccah.