There’s a free Windows utility called BeCyPDFMetaEdit that will help to remove passwords from PDF files but without make any other change to the document.

Here are the steps you need to do:

a. Launch the program and it will ask you for the location of the PDF file.

b. Before opening the PDF, change the mode to “Complete Rewrite.”

c. Select the Security tab and set the “Security System” to “No encryption.” Click the Save button and the PDF will no longer require a password to open