There was a thread telling vendors NOT to store any information on their machines. While that would be the ideal solution, it is not the one people will always use. I pointed out hidden volumes in the comments and it got some attention, so I figured I'd make a post about it.
How it works: https://veracrypt.codeplex.com/wikipage?title=Hidden%20Volume
A hidden volume is a volume that will only be visible if you type the right password into the bootloader. Otherwise, it will look like empty space on the end of the partition table. This is useful for vendors, because they can give LE the password to the decoy volume, with no real incriminating evidence, and LE would not be able to access or otherwise prove the existence of, the hidden volume.
*It's still better to delete all the data, but if you must.
I only have a couple of customers who need me to keep their shipping details. I used a pen and paper to foil the NSA's multi-billion dollar electronic surveilance coumtermeasures.
If you order from the same vendor regularly, don't insist on him forgetting your name and address. It just means you will have to encrypt it again and get it past law enforcement agencies again and again and again and again and again.
your details are all over every marketplace's servers because of this paranoid insistance. Its fine for one-off orders, but not with vendors you've been using for years.