How to change OS disk SKU for Virtual Machine Scale Set (VMSS)?

Question

I create Azure Kubernetes Service by Bicep like below.

   bicep  
   param clusterName string = 'kubernetes'  
   param location string = resourceGroup().location  
     
   resource aksCluster 'Microsoft.ContainerService/managedClusters@2022-02-01' = {  
     name: clusterName  
     location: location  
     sku: {  
       name: 'Basic'  
       tier: 'Free'  
     }  
     identity: {  
       type: 'SystemAssigned'  
     }  
     properties: {  
       kubernetesVersion: '1.23.5'  
       enableRBAC: true  
       agentPoolProfiles: [  
         {  
           name: 'agentpool'  
           mode: 'System'  
           type:'VirtualMachineScaleSets'  
           orchestratorVersion: '1.23.5'  
           enableAutoScaling: false  
           enableFIPS: false  
           maxPods: 110  
           count: 1  
           vmSize: 'Standard_B2s'  
           osType:'Linux'  
           osSKU:'Ubuntu'  
           osDiskType: 'Managed'  
           osDiskSizeGB: 0  
           enableUltraSSD: false  
           enableNodePublicIP: false  
         }  
       ]  
       dnsPrefix: 'kubernetes-cluster-dns'  
       networkProfile: {  
         loadBalancerSku: 'basic'  
         networkPlugin: 'kubenet'  
       }  
     }  
   }  

Azure Kubernetes Service (AKS) create Virtual Machine Scale Set like below.

I do not want to use Premium SSD LRS OS disk. It is too expensive for me while learning kubernetes.

What should I do?