How to cancel sell stop order when buy stop order is filled, or the other way around?

[Betican]

I am working on a breakout strategy that triggers a buy when the price breaks above a recent high, or a short if it falls below a recent low. When one of these happens, how can I cancel the other order? Thanks for any help you can offer me.

[NinjaTrader_PaulH]

Hello Betican,

Thanks for your post and welcome to the NinjaTrader forums!

NinjaTrader strategies by default will use the "Managed approach" which has rules to prevent unwanted positions, provide order handling error protection and you would not be able to place two entry type orders at once as the second order will be ignored. To accomplish your goal here you would need to have your script monitor price and then place market orders when the breakout occurs.
References:

https://ninjatrader.com/support/helpGuides/nt8/NT%20HelpGuide%20English.html?managed_approach.htm

Alternately, to accomplish your goal you could use the "UnManaged Approach" which allows you to place orders as you wish but you will have to handle all aspects of order management. In your case here you would assign an OCO value between the two entry orders to accomplish one cancels the other.
References:

https://ninjatrader.com/support/helpGuides/nt8/NT%20HelpGuide%20English.html?unmanaged_approach.htm

https://ninjatrader.com/support/helpGuides/nt8/NT%20HelpGuide%20English.html?submitorderunmanaged.htm