Hi @Siva
You can use azure cli to manage Azure backup. It has commands to [list items associated to a backup policy(https://learn.microsoft.com/en-us/cli/azure/backup/policy?view=azure-cli-latest#az-backup-policy-list-associated-items) and the backup item set-policy command enables you to change the policy associated with a backup item.
For example you can get a list of associated items for a backup policy:
az backup policy list-associated-items --name MyBackupPolicy --resource-group MyResourceGroup --vault-name MyVault --backup-management-type AzureIaasVM
And change the associated backup policy:
az backup item set-policy --vault-name MyVault --resource-group MyResourceGroup --container-name MyContainer --name MyItem --policy-name MyPolicy --backup-management-type AzureIaasVM
Alternatively you can use PowerShell:
Get the items for a container in Azure Backup: Get-AzRecoveryServicesBackupItem
Change the policy assigned to a backup item: Enable-AzRecoveryServicesBackupProtection