I have the following script. I use the original to remove page images, but the process is similar, so I just changed it to remove the text instead.

            bool success = true;

            DocumentInfo doc = (DocumentInfo)this.BoundEntryInfo;
            doc.Lock(LockType.Exclusive);

            try{
                // Read values of each page
                PageInfoReader pageReader = doc.GetPageInfos();
                foreach(PageInfo page in pageReader){
                    // check if page has text and remove it
                    if(page.HasText){
                        page.ClearPagePart(PagePart.Text);
                    }
                }

                // Save changes
                doc.Save();
            }
            catch(Exception ex){
                // Flag for retry
                success = false;
                WorkflowApi.TrackError(ex.Message);
            }
            finally{
                // Release document
                doc.Unlock();
                doc.Dispose();

                // Set output
                SetTokenValue("Success",success);
            }