FileFlex allows you to edit PDF files without requiring any third-party PDF application. FileFlex allows users to have advanced PDF editing , redaction and cropping using Fileflex itself.
How to edit PDF using FileFlex
Open the PDF file you want to edit.
From the menu click " Edit using FileFlex Enterprise "
This will open up new options in the file top bar, where you can choose to edit or redact a file.
Under EDIT mode you can crop your pages during crop icon 
Click 
to edit your file.
Clicking this icon breaks the page into different components that can be modified individually just like any other PDF editor.
Double-clicking inside the box provides you with a text box where text can be modified as shown below.
PDF Redaction
Click on redaction sub menu.
This provides you redaction toolbar to redact sections of PDF.
Once a text is redacted, the changes can be applied by clicking on APPLY or by saving the document.
FileFlex also provides a redaction panel where all changes can be viewed and applied in one go.
Note: Changes applied via PDF editing and Redaiton are permanent and modify the original PDF. If your content source doesn't support revisioning then you may want to take a backup copy in case of erroneous edits.