Removing text from PDF-s

Step 1: Convert the PDF into one which has (nearly) all PDF objects' contents and streams expanded into a readable form using QPDF.

   qpdf --qdf --object-streams=disable input.pdf output.pdf 
    

Step 2: Open using an text editor and replace all instances of the keyword 'font' with anything really.

Step 3: ???

Step 4: Profit

NB: Modify the 'TJ' tags of the stream objects to remove specific texts.