You could use Azure Rest API to do this.
PUT https://management.azure.com/subscriptions/***********/resourceGroups/shui156/providers/Microsoft.Sql/servers/shui156/databases/shui156/geoBackupPolicies/Default?api-version=2014-04-01
Body:
{
"id": "/subscriptions/***********/resourceGroups/shui156/providers/Microsoft.Sql/servers/shui156/databases/shui156/geoBackupPolicies/Default",
"name": "Default",
"type": "Microsoft.Sql/servers/databases/geoBackupPolicies",
"location": "East US",
"kind": null,
"properties": {
"state": "Disabled",
"storageType": null
}
}