Delete all row accept 1 from selected total rows in sql

Question

I have one table it contains many duplicate rows for single value.for eg below

 

suppose there is one record with above ACCS_NO= 004068 value.with this value there are total 3 rows with same records accept doc_no.so I want to delete top 2 from 3

records i.e.  doc_no=008446 & 008447(here in this table doc_no is auto generated id).I want to do this for whole table at one time in sql only.

 

please help to solve this problem.how can I do this?I want to do this for all duplicate records?