wr_process.py

from PyPDF2 import PdfFileReader, PdfFileWriter

DOWNLOAD_FOLDER = os.path.dirname(os.path.abspath(__file__)) + '/downloads/'

app.config['DOWNLOAD_FOLDER'] = DOWNLOAD_FOLDER

def process_file(path, filename):
   remove_watermark(path, filename)

def remove_watermark(path, filename):
   input_file = PdfFileReader(open(path, 'rb'))
   output = PdfFileWriter()
   for page_number in range(input_file.getNumPages()):
       page = input_file.getPage(page_number)
       page.mediaBox.lowerLeft = (page.mediaBox.getLowerLeft_x(), 20)
       output.addPage(page)
   output_stream = open(app.config['DOWNLOAD_FOLDER'] + filename, 'wb')
   output.write(output_stream)