Remove permissions

I've downloaded several bank statements from my bank and have tried to combine them into one file using the Combine method.

I am getting a message that I need a permission password to do that. My bank tells me that the statements are encrypted to avoid alteration which is fine and they don't put a password on them.

So where is the password so I can combine the files and what else is there as another option to combine them?

Using version 2020.012.20043 and Windows 10.

Thanks for any help on this.