Remove moveToTrash feature for QT versions pre 5.15

The settings entry is hidden when the QT version is not supported
The file is always permanently deleted - dialog box indicates this.

src/contentmanager.cpp

@@ -461,10 +461,14 @@ void ContentManager::eraseBookFilesFromComputer(const QString dirPath, const QSt
     }
     QDir dir(dirPath, fileName);
     for(const QString& file: dir.entryList()) {
+#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
         if (moveToTrash)
             QFile::moveToTrash(dir.filePath(file));
         else
             dir.remove(file);
+#else
+        dir.remove(file); // moveToTrash will always be false here, no check required.
+#endif
     }
 }
 
@@ -479,7 +483,10 @@ QString formatText(QString text)
 void ContentManager::eraseBook(const QString& id)
 {
     auto text = gt("delete-book-text");
-    const auto moveToTrash = KiwixApp::instance()->getSettingsManager()->getMoveToTrash();
+    auto moveToTrash = KiwixApp::instance()->getSettingsManager()->getMoveToTrash();
+#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
+    moveToTrash = false; // we do not support move to trash functionality for qt versions below 5.15
+#endif
     if (moveToTrash) {
         text += formatText(gt("move-files-to-trash-text"));
     } else {

src/settingsview.cpp

@@ -34,6 +34,11 @@ SettingsView::SettingsView(QWidget *parent)
     ui->monitorHelp->setText("<b>?</b>");
     ui->monitorHelp->setToolTip(gt("monitor-directory-tooltip"));
     ui->moveToTrashLabel->setText(gt("move-files-to-trash"));
+#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
+    ui->moveToTrashLabel->hide();
+    ui->moveToTrashToggle->hide();
+#endif
+
 }
 
 void SettingsView::init(int zoomPercent, const QString &downloadDir, const QString &monitorDir, const bool moveToTrash)