I have a workbook with 10 sheets. Each sheet will have
50,000 or more rows. Col A is a reference number for each
row of data. Reference numbers are repeated thoughout the
each sheet.

What I need to do is reduce each sheet to only 1 instance
of each unique reference number. I was able to compare
each row to the one above and delete it if the reference
is the same. (for example, each sheet will only contain
7,000 - 9,000 records after it is reviewed.) While this
works it is time-consuming with over 500,000 rows to
review.

Is there a better / quicker way to reduce each sheet to
display 1 instance of each unique value in col A?

Thanks for the help.