how to remove duplicates on numbers app

There are various ways, depending on what you want to do. One of the simplest is to just use a filter:

Then if you want the "deduplicated" list elsewhere just select the cells, command-c to copy, click once in a cell of another existing table, and command-v to paste.

SG

You can also use a Pivot Table.

Click in the table with the duplicate data, choose Organize > Create Pivot Table > On Current Sheet, then drag the fields like this in the Pivot Options pane:

Then copy-paste column A of the Pivot Table where you want the data.

SG

a third method that I have used for a long time, is a countIF

This is useful when you dont want to make a new table of data, just want to identify the duplicate rows (sometimes to note where they are and sometimes to delete them)

I add a formula to count how many times my Key had occurred from current row up to the top.

To delete those rows. copy/paste formula results over that column, sorta ascending, find the first number >1 and delete everything under that row.

Jason