Assuming data start in A1 and occupy three columns.

Insert two columns between A:A and B:B. Next to A1 enter the formula:

=COUNTIF(D:E, A1)<1

and copy down. Apply Data|Filter|AutoFilter and select the rows that
display TRUE in B:B. Select and erase those data.

Delete the inserted columns B:C. Repeat the process between original
columns B:C. Use in C1:

=COUNTIF(F:F, B1)<1

At the end of the second round all three columns will contain globally
unique data. COpy and paste in a single column if desired
(recommended).

HTH
Kostis Vezerides