Unable to clear RollingUpgradePolicy in Virtual Machine Scaleset

[RollingUpgradePolicy](https://docs.microsoft.com/en-us/rest/api/compute/virtualmachinescalesets/createorupdate#rollingupgradepolicy) is an optional parameter in Virtual Machine Scaleset. But I'm not able to remove it once it is set. I tried using `null`, using empty object `{}`, I also tried pass nothing, but no luck to succeed.

Thanks.

Start with the linked Virtual Machine Scale Sets REST API documentation and reproduce updates using null, an empty object, and an omitted RollingUpgradePolicy. Determine whether the API specification or service behavior prevents clearing an existing policy; done when the expected clearing behavior is documented or the relevant API definition is corrected.

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