Removed obsolete removeImage method

It does not make sense to remove single images

Libs/DICOM/Core/ctkDICOMDatabase.cpp

@@ -798,12 +798,7 @@ bool ctkDICOMDatabase::isInMemory() const
   Q_D(const ctkDICOMDatabase);
   return d->DatabaseFileName == ":memory:";
 }
-/*
-bool ctkDICOMDatabase::removeImage(const QString& sopInstanceUID)
-{
-  return false;
-}
-*/
+
 bool ctkDICOMDatabase::removeSeries(const QString& seriesInstanceUID)
 {
   Q_D(ctkDICOMDatabase);

Libs/DICOM/Core/ctkDICOMDatabase.h

@@ -145,7 +145,6 @@ public:
   /// Check if file is already in database and up-to-date
   bool fileExistsAndUpToDate(const QString& filePath);
 
-  // bool removeImage(const QString& sopInstanceUID);
   /// remove the series from the database, including images and
   /// thumbnails  
   bool removeSeries(const QString& seriesInstanceUID);