List of authorized devices / Deauthorized devices

I've reached the maximum of authorized devices but most of them are no longer available (pc's or eareders on the trash).

I know I can deauthorized a device when conected but...how can I do that without conect that device? Can I get a list of authorized devices and do it from there?

If that's not possible, I would deauthorized all actual devices -I mean to reset all authorizations (so later I can authorized again the pc and ereader I follow nowadays).

Thanks in advance for your help.