Sorting by date

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I want the oldest date corresponding to the code. For example, in the given image, code starting with ES has oldest date of 18-09-09. I want the other entries to be removed. I have nearly 1000 codes with similar format. I want to get the code along with the oldest date of posting. How to do this?

Sample file - https://www.dropbox.com/s/e83khgg2a4...orum.xlsx?dl=0