When receiving a signed document how do I attach to a file

I sent a document to be signed by a party.  They e signed it and returned but the file is locked so I can't attach it to a bigger file.  I can't print a pdf with it either.  How do I disable the lock so this does not happen again.  There is really no benefit of this if we have to print it, scan it to be able to attach to the larger file every time.  How can we avoid doing all the extra work?