I made an alias that includes all the screen names I play under. Purged my database with these options.
Cash -> All Stakes -> Save Hands played by [Alias] -> All Sites -> All Dates
It purged my entire database. Lost all of my hands played under any screen name.
Luckily, I had created a new db for HM2 and imported everything from my old db, so I had a backup. I imported from the old db, but it doesn't import anything. The bar will move as though its working, but it just says 0 of 1,779,000 imported. I have tried it with both Hero only and All checked.