[C#]
// Set up the CRM Service.
CrmAuthenticationToken token = new CrmAuthenticationToken();
token.AuthenticationType = 0; 
token.OrganizationName = "AdventureWorksCycle";

CrmService service = new CrmService();
service.Url = "http://<servername>:<port>/mscrmservices/2007/crmservice.asmx";
service.CrmAuthenticationTokenValue = token;
service.Credentials = System.Net.CredentialCache.DefaultCredentials;

// Create a query expression that retrieves all accounts.
QueryExpression accountsQuery = new QueryExpression();
accountsQuery.EntityName = EntityName.account.ToString();
// Be aware that using AllColumns may adversely affect
// performance and cause unwanted cascading in subsequent 
// updates. A best practice is to retrieve the least amount of 
// data required.
accountsQuery.ColumnSet = new AllColumns();

// Create a query expression that retrieves all contacts.
QueryExpression contactsQuery = new QueryExpression();
contactsQuery.EntityName = EntityName.contact.ToString();
// Be aware that using AllColumns may adversely affect
// performance and cause unwanted cascading in subsequent 
// updates. A best practice is to retrieve the least amount of 
// data required.;
contactsQuery.ColumnSet = new AllColumns()

// Create a request.
BulkDeleteRequest request = new BulkDeleteRequest();
request.JobName = "Delete all accounts and contacts";
request.QuerySet = new QueryBase[] { accountsQuery, contactsQuery }; 
request.SendEmailNotification = false;
request.ToRecipients = new Guid[0];
request.CCRecipients = new Guid[0];
request.RecurrencePattern = string.Empty;
request.StartDateTime = new CrmDateTime();
request.StartDateTime.Value = DateTime.Now.ToString("s");

// Execute the request.
BulkDeleteResponse response = (BulkDeleteResponse)service.Execute(request);
Guid jobId = response.JobId;

[Visual Basic .NET]
' Set up the CRM Service.
Dim token As New CrmAuthenticationToken()
' You can use enums.cs from the SDK\Helpers folder to get the enumeration for Active Directory authentication.
token.AuthenticationType = 0
token.OrganizationName = "AdventureWorksCycle";
 
Dim service As New CrmService()
service.Url = "http://<servername>:<port>/mscrmservices/2007/crmservice.asmx";
service.CrmAuthenticationTokenValue = token;
service.Credentials = System.Net.CredentialCache.DefaultCredentials

' Create a query expression that retrieves all accounts
Dim accountColumns As New ColumnSet()
accountColumns.Attributes = New String() {"name"}

Dim accountIdsCondition As New ConditionExpression()
accountIdsCondition.AttributeName = "accountid"
accountIdsCondition.Operator = ConditionOperator.In
accountIdsCondition.Values = New Object() {accountIds(0), accountIds(1), accountIds(2)}

Dim accountIdsFilter As New FilterExpression()
accountIdsFilter.Conditions = New ConditionExpression() {accountIdsCondition}

Dim accountsQuery As New QueryExpression()
accountsQuery.EntityName = EntityName.account.ToString()
accountsQuery.ColumnSet = accountColumns
accountsQuery.Criteria = accountIdsFilter

' Create a query expression that retrieves all contacts
Dim contactColumns As New ColumnSet()
contactColumns.Attributes = New String() {"fullname"}

Dim contactIdsCondition As New ConditionExpression()
contactIdsCondition.AttributeName = "contactid"
contactIdsCondition.Operator = ConditionOperator.In
contactIdsCondition.Values = New Object() { contactIds(0), contactIds(1), contactIds(2)}

Dim contactIdsFilter As New FilterExpression()
contactIdsFilter.Conditions = New ConditionExpression() { contactIdsCondition }

Dim contactsQuery As New QueryExpression()
contactsQuery.EntityName = EntityName.contact.ToString()
contactsQuery.ColumnSet = contactColumns
contactsQuery.Criteria = contactIdsFilter

' Create a request
Dim request As New BulkDeleteRequest()
request.JobName = "Delete all accounts and contacts"
request.QuerySet = New QueryBase() { accountsQuery, contactsQuery }
request.SendEmailNotification = False
request.ToRecipients = New Guid(){}
request.CCRecipients = New Guid(){}
request.RecurrencePattern = String.Empty
request.StartDateTime = New CrmDateTime()
request.StartDateTime.Value = DateTime.Now.ToString("s")

' Execute the request
Dim response As BulkDeleteResponse = CType(service.Execute(request), BulkDeleteResponse)
Dim jobId As Guid = response.JobId