@Mahesh39 Aspose.Words do not remove transparency when saving to PDF and keeps the transparent objects as they are in the source Microsoft Word document. The only exception is saving to PDF/A-1 compliance where transparency is prohibited by specification. In this case Aspose.Words removes the transparency but it may cause visual difference comparing to the source document.
If you want to remove transparency you should do it by yourself either in source document or by postprocessing Aspose.Words PDF output.
@Mahesh39 For preprocessing the document, you can try rendering your shape to the format that does not support transparency, for example to Jpeg (original format of the image in the document is EMF metafile). You can do this using ShapeRenderer. But this might lead to quality degradation since EMF metafile is vector format, but Jpeg is raster.
Regarding postprocessing it is better to ask in Aspose.PDF forum. my colleagues from Aspose.PDF team will help you shortly.