public bool Deactivate(AuthorEncryptionKey encryptionKey,
    string installationId, ref LicenseError lastError)
{
    //make sure we have an Installation ID to use first
    if (string.IsNullOrEmpty(installationId))
    {
        lastError = new LicenseError(LicenseError.ERROR_INSTALLATIONID_REQUIRED);
        return false;
    }

    DeactivateInstallation ws = new DeactivateInstallation(encryptionKey);
    ws.InstallationID = installationId;

    XmlActivationService client = new XmlActivationService();
    // If you are using SOLO Server Dedicated URL or a self-hosted instance of SOLO Server,
    // set the client.Url property here.  You may also configure proxy settings on this object here, if necessary.
    ws.WebServiceClient = client;

    if (!ws.CallWebService())
    {
        //If you wish to revoke the local license, you can add code to do so here.
        lastError = ws.LastError;
        return false;
    }

    return true;
}

Public Function Deactivate(ByVal encryptionKey As AuthorEncryptionKey, _
    ByVal installationId As String, ByRef lastError As LicenseError) As Boolean

    //make sure we have an Installation ID to use first
    If String.IsNullOrEmpty(installationId) Then
        lastError = new LicenseError(LicenseError.ERROR_INSTALLATIONID_REQUIRED)
        Return False
    End If

    Dim ws As New DeactivateInstallation(encryptionKey)
    ws.InstallationID = installationId

    Dim client As New XmlActivationService()
    'If you are using SOLO Server Dedicated URL or a self-hosted instance of SOLO Server,
    ' set the client.Url property here.  You may also configure proxy settings on this object here, if necessary.
    ws.WebServiceClient = client

    If Not ws.CallWebService() Then
        'If you wish to revoke the local license, you can add code to do so here.
        lastError = ws.LastError
        Return False
    End If

    Return True
End Function

No code example is currently available or this language may not be supported.