How to move kubernetes to a different subscription in azure?

I have two subscriptions under my account. When I check today, the balance is low in my subscription where I deployed the cluster.

So, I click on change subscription option and selected the second subscription in my account.

But, getting below error.

{"code":"ResourceMoveValidationFailed","message":"The resource batch move request has '1' validation errors. Diagnostic information: timestamp '20210708T074027Z', tracking Id 'bae55f37-137e-4388-ba57-a46456b5efb9', request correlation Id '2ffbd2bc-1198-42ec-b8c5-60cbaed7a160'.","details":[{"code":"ResourceMoveNotSupported","target":"/subscriptions/f733ab10-e6a2-406d-9c23-cafe4ec0e71e/resourceGroups/testmart/providers/Microsoft.ContainerService/managedClusters/testmart","message":"Resource move is not supported for resource types 'Microsoft.ContainerService/managedClusters'."}]}

How to move the cluster then?

As per I see - you are not able to change subscription for Microsoft.ContainerService.managedClusters, so I would say no way for an action you are trying to perform

Check Move operation support for resources - Microsoft.ContainerService part

You cannot move AKS clusters. You would need to recreate the cluster in the new sub and migrate workloads.