Delete all accounts ? after rollback/history, still present !

Delete all accounts ? after rollback/history, still present !

I am new (Entr.Version),started importing into CRM/Accounts  a 16000 accounts,but see,
 there are many duplicates, in spite of clone.
 
I did rollback to clean the accounts,but data still there.
How to clean up/delete all accounts.?
 
Thanks
William