delete dupes macro

I require a delete dupes macro that verifies 3 different columns:

columns A = employee id, B = client id, c = date with time stamp.

query needs to:

1) identify all duplicate client ids (column b)
2) within duplicate client ids(column b), identify duplicate employee ids (column a)
3) within dupicate client ids (column b) and duplicate employee ids (column a) delete row for older date in (column c) based on time stamp.