'Usage

Dim instance As Versions
Dim fileName As String
Dim fileVersion As String
Dim returnValue As XmlNode

returnValue = instance.DeleteVersion(fileName, fileVersion)

'Declaration

<SoapDocumentMethodAttribute("http://schemas.microsoft.com/sharepoint/soap/DeleteVersion", RequestNamespace:="http://schemas.microsoft.com/sharepoint/soap/", ResponseNamespace:="http://schemas.microsoft.com/sharepoint/soap/", Use:=SoapBindingUse.Literal, ParameterStyle:=SoapParameterStyle.Wrapped)> _
Public Function DeleteVersion ( _
    fileName As String, _
    fileVersion As String _
) As XmlNode

Dim versionService As New Web_Reference_Folder_Name.Versions()
versionService.Credentials = 
   System.Net.CredentialCache.DefaultCredentials

Dim ndVersions As XmlNode = 
   versionService.DeleteVersion("Shared Documents/File_Name", "3")

MessageBox.Show(ndVersions.OuterXml)