SQL: Removing Duplicates in one column while retaining the row with highest value in another column -

i using teradata , stuck trying write code... remove rows in columnb has duplicate value, based on values in columna - if can me great!

i have sequencial number in columna , retain row highest value in columna. eg. in below table retain rows 9,7,6 & 2, because although have duplicate in column 2 have highest columna value letter.

table name: datatable

column1    column2     column3     column4     column5       1           b           x           x           x      2                     y           y           y      3           e           z           z           z      4           b           x           x           x      5           c           y           y           y      6           e           z           z           z      7           c           x           x           x      8           b           y           y           y      9           b           z           z           z 

if want select rows, can do:

select t.* t t.columna = (select max(t2.columna) t t2 t2.columnb = t.columnb); 

if want remove them, 1 method is:

delete t t.columna < (select max(t2.columna) t t2 t2.columnb = t.columnb);