diff --git a/Applications/FileIO/XmlIO/Qt/XmlNumInterface.cpp b/Applications/FileIO/XmlIO/Qt/XmlNumInterface.cpp
deleted file mode 100644
index 2b32cf6504cfd22f1d8a15ff72c20feb5a32ea31..0000000000000000000000000000000000000000
--- a/Applications/FileIO/XmlIO/Qt/XmlNumInterface.cpp
+++ /dev/null
@@ -1,148 +0,0 @@
-/**
- * \file
- * \author Karsten Rink
- * \date   2014-08-05
- * \brief  Implementation of the XmlNumInterface class.
- *
- * \copyright
- * Copyright (c) 2012-2021, OpenGeoSys Community (http://www.opengeosys.org)
- *            Distributed under a Modified BSD License.
- *              See accompanying file LICENSE.txt or
- *              http://www.opengeosys.org/project/license
- *
- */
-
-#include "XmlNumInterface.h"
-
-#include <QFile>
-#include <QTextCodec>
-#include <QtXml/QDomDocument>
-
-#include "BaseLib/Logging.h"
-
-namespace FileIO
-{
-XmlNumInterface::XmlNumInterface() : XMLQtInterface("OpenGeoSysNUM.xsd") {}
-
-int XmlNumInterface::readFile(QString const& fileName)
-{
-    if (XMLQtInterface::readFile(fileName) == 0)
-    {
-        return 0;
-    }
-
-    QDomDocument doc("OGS-NUM-DOM");
-    doc.setContent(_fileData);
-    QDomElement const docElement = doc.documentElement(); //OGSNonlinearSolverSetup
-    if (docElement.nodeName().compare("OGSNonlinearSolverSetup"))
-    {
-        ERR("XmlNumInterface::readFile() - Unexpected XML root.");
-        return 0;
-    }
-
-    QDomElement num_node = docElement.firstChildElement();
-
-    while (!num_node.isNull())
-    {
-        if (num_node.nodeName().compare("Type") == 0)
-        {
-            std::string const solver_type = num_node.toElement().text().toStdString();
-            INFO("Non-linear solver type: {:s}.", solver_type);
-        }
-        else if (num_node.nodeName().compare("LinearSolver") == 0)
-        {
-            readLinearSolverConfiguration(num_node);
-        }
-        else if (num_node.nodeName().compare("IterationScheme") == 0)
-        {
-            readIterationScheme(num_node);
-        }
-        else if (num_node.nodeName().compare("Convergence") == 0)
-        {
-            readConvergenceCriteria(num_node);
-        }
-
-        num_node = num_node.nextSiblingElement();
-    }
-
-    return 1;
-}
-
-void XmlNumInterface::readLinearSolverConfiguration(QDomElement const& lin_root)
-{
-    std::string const library = lin_root.attribute("Library").toStdString();
-    std::string lin_solver_type;
-    std::string precond_type("no");
-
-    QDomElement linear_solver_node = lin_root.firstChildElement();
-    while (!linear_solver_node.isNull())
-    {
-        if (linear_solver_node.nodeName().compare("Type") == 0)
-        {
-            lin_solver_type =
-                linear_solver_node.toElement().text().toStdString();
-        }
-        if (linear_solver_node.nodeName().compare("Preconditioner") == 0)
-        {
-            precond_type = linear_solver_node.toElement().text().toStdString();
-        }
-        linear_solver_node = linear_solver_node.nextSiblingElement();
-    }
-    INFO("Using {:s}-library with solver {:s} and {:s} preconditioner.",
-         library, lin_solver_type, precond_type);
-}
-
-
-void XmlNumInterface::readIterationScheme(QDomElement const& iteration_root)
-{
-    QDomElement iteration_node = iteration_root.firstChildElement();
-    int max_iterations(0);
-    int fixed_step_size(0);
-
-    while (!iteration_node.isNull())
-    {
-        if (iteration_node.nodeName().compare("MaxIterations") == 0)
-        {
-            max_iterations = iteration_node.toElement().text().toInt();
-        }
-        if (iteration_node.nodeName().compare("FixedStepSize") == 0)
-        {
-            fixed_step_size = iteration_node.toElement().text().toInt();
-        }
-
-        iteration_node = iteration_node.nextSiblingElement();
-    }
-    INFO("Doing a maximum of {:d} iterations at fixed step size of {:f}",
-         max_iterations, fixed_step_size);
-}
-
-void XmlNumInterface::readConvergenceCriteria(QDomElement const& convergence_root)
-{
-    QDomElement conv_node = convergence_root.firstChildElement();
-    double error_threshold(0);
-    std::string error_method;
-
-    while (!conv_node.isNull())
-    {
-        if (conv_node.nodeName().compare("Method") == 0)
-        {
-            error_method = conv_node.toElement().text().toStdString();
-        }
-        if (conv_node.nodeName().compare("ErrorThreshold") == 0)
-        {
-            error_threshold = conv_node.toElement().text().toDouble();
-        }
-
-        conv_node = conv_node.nextSiblingElement();
-    }
-    INFO("Convergence reached when error below {:f} using {:s}.",
-         error_threshold, error_method);
-}
-
-bool XmlNumInterface::write()
-{
-    INFO("Not yet implemented...");
-    return false;
-}
-
-}  // namespace FileIO
diff --git a/Applications/FileIO/XmlIO/Qt/XmlNumInterface.h b/Applications/FileIO/XmlIO/Qt/XmlNumInterface.h
deleted file mode 100644
index 39411d89cc37219be79f7c36a6e6a03c297914aa..0000000000000000000000000000000000000000
--- a/Applications/FileIO/XmlIO/Qt/XmlNumInterface.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/**
- * \file
- * \author Karsten Rink
- * \date   2014-08-05
- * \brief  Definition of the XmlNumInterface class.
- *
- * \copyright
- * Copyright (c) 2012-2021, OpenGeoSys Community (http://www.opengeosys.org)
- *            Distributed under a Modified BSD License.
- *              See accompanying file LICENSE.txt or
- *              http://www.opengeosys.org/project/license
- *
- */
-
-#pragma once
-
-#include "BaseLib/IO/XmlIO/XMLInterface.h"
-#include "BaseLib/IO/XmlIO/Qt/XMLQtInterface.h"
-
-namespace FileIO
-{
-
-class XmlNumInterface : public BaseLib::IO::XMLInterface, public BaseLib::IO::XMLQtInterface
-{
-public:
-    XmlNumInterface();
-
-    ~XmlNumInterface() override = default;
-
-    int readFile(QString const& fileName) override;
-
-    bool readFile(std::string const& fname) override
-    {
-        return readFile(QString(fname.c_str())) != 0;
-    }
-
-protected:
-    void readLinearSolverConfiguration(QDomElement const& lin_root);
-    void readIterationScheme(QDomElement const& iteration_root);
-    void readConvergenceCriteria(QDomElement const& convergence_root);
-    bool write() override;
-};
-
-}  // namespace FileIO