To cancel the order, right-click it -> Cancel Order.
To cancel all active orders for all symbolsfor all the broker profiles and accounts, right-click one of the orders -> Cancel All Orders.
To cancel all active orders for the particular symbol, right-click one of the orders -> Cancel All Orders for This Symbol.
To cancel all active orders and close all open positionsfor all the broker profiles and accounts, right-click one of the orders -> Flatten Everything.
To change the price of an active order, right-click it -> Change Stop Price /Change Limit Price.