"UPDATE" INSTEAD OF "ADDING" A NEW IMAGE?

"UPDATE" INSTEAD OF "ADDING" A NEW IMAGE?

CODE:
https://codepen.io/juscelinobarao/pen/bLLdZx

The above code always displays a thumbnail when an image is chosen.
But if I choose three different images three times - or not - the code will list me three different thumbnailS with the three images.

How to discard the previous image when choosing a new image, without listing all the chosen ones?


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Atenciosamente
Juscelino Barão