To delete currencies you have added to Bokun you can go to your price catalogue and delete the currency. To delete the currency means that you remove it from your price catalogues, then you can always add it back later if needed.
To delete currencies go to your pricing by selecting "Products" on the top bar, then you select "Pricing" from the drop own list.
To delete a currency, start by selecting the currency, from the currency drop down list. When you have select the currency, then a "delete" buttons appears. Press the delete button to delete the currency.