Have received a PDF file on iPhone which is password protected and need to remove the password? It is very cumbersome to keep track of various long passwords. If someone sent you a PDF file with password, you can delete its password or replace it with a new password which is easier to remember. There are some third-party apps can do that, like the Documents app which is available for free on App Store.
Here is how to remove password from PDF file on iPhone iPad using the free file manager app.
Find the PDF file in the Files or other app where the PDF file is saved, select it, tap the action menu, then choose Open in Documents. You will then be prompted to type in the password in order to open it. Once the PDF file is opened in the Documents app, tap the Menu button, then choose Change Password. In the next screen, you can change the PDF password or remove it. See below figure.
Now you will be able to open the PDF file on your iPhone, iPad or other devices without authentication. It is just that easy.