Adobe apps can be reset to their factory defaults by using Ctrl+Alt+Shift, not Del. The rest doesn't really make any sense since you did not provide any details and authorizations can't be changed that way, anyway. If you want to transfer books to other devices you need to contact the vendors to release the DRM/ provide a new download and if you want to change the registered ID, you need to contact support or create a completely new account, which in turn will require you to buy your DRM managed books again/ get a new download as well.
ctrl-shift-D will remove your old authorization to ADE; you will then be able to add a new one.
But as Mylenium points out, be aware you will lose access to your old DRM books on that Vista system.
You could still revert to the original if you needed.