An open password stops anyone reading the file at all. An owner password lets the file open but blocks printing, copying or editing. Unlock removes both, as long as you have the open password when the file asks for one.
It does not guess or crack passwords. If you have forgotten the open password, the file cannot be recovered. Only unlock files that are yours or that you have permission to open.
Open the Unlock tab in the PDF Toolkit, add the file, type the password if the file asks for one, and press Remove protection. You get a copy with no password and no restrictions.
Bank statements, contracts and IDs are exactly the files that carry passwords. The work happens in your browser with the qpdf engine, so the file and the password never leave your device.
Open the free PDF ToolkitNo page limit and offline use: the one-time $19 offline pack is here: https://xargaartools.gumroad.com/l/pdf-toolkit-offline-pack