Deleting rows based on duplicates in one column only

Not sure if that explains it.

I have multiple entries for each Id no (column AL) and I want to identify and remove all duplicates. Even though there are some variants as you go across the row, it doesn't matter if the whole row gets deleted (I don't need to merge the rows). In the example attached, I should end up with four rows. Is there a simple(ish) way of doing this? Please bear in mind, I can cut and paste like a genius but have little understanding of why all these fixes work!

Thanks

K