Examples-GroupDocs.Metadata-for-Java
// initialize DocFormat
DocFormat docFormat = new DocFormat(Common.mapSourceFilePath(path));
//Use one of the following methods
//Method 1 - clear custom properties
//docFormat.clearCustomProperties();
//Method 2 - clear custom properties
docFormat.getDocumentProperties().clearCustomData();
// commit changes
docFormat.save(Common.mapDestinationFilePath(outputPath));