How to activate "Automatic Deallocation" setting in the contract item category for purchase contract

[Hems]

Hi All,

Please advise how to activate the "Automatic Deallocation" setting in the contract item category for the purchase contract and help with the configuration steps.

Once you have created a contract and release order, then you decrease the quantity on the release order or delete the release order. quantity deleted/decreased should not go back to the contract.

Thanks,

Hems