code: def dropStudyFromISA(studyNum, pathToISATABFile):
      
      from isatools import isatab
      import os
      try:
          isa = isatab.load(pathToISATABFile, skip_load_tables=True)
          studies = isa.studies
          for assay in studies[studyNum - 1].assays:
              if os.path.isfile(os.path.join(pathToISATABFile,assay.filename)):
                  os.remove(os.path.join(pathToISATABFile,assay.filename))
          if os.path.isfile(os.path.join(pathToISATABFile,studies[studyNum - 1].filename)):
              os.remove(os.path.join(pathToISATABFile,studies[studyNum - 1].filename))
          del studies[studyNum - 1]
          isatab.dump(isa_obj=isa, output_path=pathToISATABFile)
      except FileNotFoundError as err:
          raise err
docs: This function removes a study from an ISA file
      Typically, you should use the exploreISA function to check the contents
      of the ISA file and retrieve the study number you are interested in!
      Warning: this function deletes the given study and all its associated assays
      :param studyNum: The Study number (notice it's 1-based index).
      :type studyNum: int
      :param pathToISATABFile: The path to the ISATAB file
      :type pathToISATABFile: string
      :raise FileNotFoundError: If pathToISATABFile does not contain file 'i_Investigation.txt'.