If you have forgotten your eM Client startup application password in Windows then see @Gary post below.
I was under the impression that deleting my old eM Client I installing a new one would resolve this issue but it didn’t.
If you uninstalled eM Client in Windows and either deleted the database when asked on the uninstall wizard or renamed the hidden database prior to uninstalling, “then you wouldn’t normally get asked for the eM Client app startup password”.
So all depends if you kept your previous mail database when you uninstalled eM Client.