Once you have used a Tax Type on a Sales Order, TradeGecko will not allow you to make any changes to the Tax Type or delete it. This is in keeping with accounting best practices.
1. Go to your Sales Orders and Delete or Void the Sales Order with that Tax Type.
If you delete your Sales Orders your stock levels and associated profits will be rolled back. The orders will not be reflected in any of your reports. If the invoice is not paid for it will be deleted on your accounting software as well.
Once you have deleted the associated Sales Order(s) go to your Tax Types under Settings. Select the tax that you need to edit/delete.
Make the changes to your tax type here.