LigarDesligarVM.cs

public class LigarDesligarVM 
{
    /* informações de token e o estado correto devem ser tratados antes*/
    public void Ligar(TokenCredentials credentialstring, string subscriptionId, string resourceGroup, string nomeDaVM)
    {
        var computeManagementClient = new ComputeManagementClient(credential) { SubscriptionId = subscriptionId };
        computeManagementClient.VirtualMachines.Start(resourceGroup, nomeDaVM);
    }
    
    public void Desligar(TokenCredentials credentialstring, subscriptionId, string resourceGroup, string nomeDaVM)
    {
        computeManagementClient = new ComputeManagementClient(credential) { SubscriptionId = subscriptionId };
        computeManagementClient.VirtualMachines.DeallocateAsync(resourceGroup, nomeDaVM);
    }
}

VerificarEstadoVM.cs

/**
 * Informações
 * https://docs.microsoft.com/pt-br/azure/active-directory/develop/howto-create-service-principal-portal
 */
public class VirtualMachine
{
    public bool Ativa { get; set; }
    public bool Code { get; set; }
    public bool DisplayStatus { get; set; }
}
public class VerificarEstadoVM 
{
    public VirtualMachine Verificar(string resourceGroup, string nomeDaVM)
    {
         var subscriptionId          = "00000000-0000-0000-0000-000000000000";
         var token                   = GetToken(entrada.NomeDaVM);
         var credential              = new TokenCredentials(token.Result.AccessToken);
         var computeManagementClient = new ComputeManagementClient(credential) { SubscriptionId = subscriptionId };
         return GetEstado(credential, subscriptionId, resourceGroup, nomeDaVM);
    }
    private Task<AuthenticationResult> GetToken()
    {
        var cc      = new ClientCredential("00000000-0000-0000-0000-000000000000", "senhaficaaqui");
        var context = new AuthenticationContext("https://login.windows.net/00000000-0000-0000-0000-000000000000");
        var token   = context.AcquireTokenAsync("https://management.azure.com/", cc);
        return token;
    }
    private VirtualMachine GetEstado(TokenCredentials credential, string subscriptionId, string resourceGroup, string nomeDaVM)
    {
        var computeManagementClient = new ComputeManagementClient(credential) { SubscriptionId = subscriptionId };
        var vmResult                = computeManagementClient.VirtualMachines.Get(resourceGroup, nomeDaVM, InstanceViewTypes.InstanceView);

        var statusVM = vmResult.InstanceView.Statuses.Where(x => x.Code.Contains("PowerState")).FirstOrDefault();
        var vm = new VirtualMachine();
        if (statusVM == null)
        {
            statusVM                      = vmResult.InstanceView.Statuses.Where(x => x.Code.Contains("ProvisioningState")).FirstOrDefault();
        }
        var ativa = statusVM.Code == "PowerState/running" || "PowerState/starting";
        return new  VirtualMachine()
        {
            Ativa         = ativa,
            Code          = statusVM.Code,
            DisplayStatus = statusVM.DisplayStatus        
        };
    }
}