To delete orders in bulk in your Shopify store first ensure that you have a worksheet linked to your Shopify store's orders. Select the rows for the orders you'd like to delete, just like you would in Excel - by clicking on the row header and dragging the mouse to cover additional row headers. Then right-click on one of the selected row headers (the row header shows the row number). In the menu that opens select the Delete object in Shopify menu option.
You'll now see a dialog show up, confirming that you want to permanently delete the selected orders in your store. Once you confirm, Mixtable will notify Shopify, asking it to delete the orders. Once the deletion is done, the orders' data will be removed from your worksheet.