To use it as your Desktop Icon you need to download the png file from here and convert it to a .ICO file on this website, you have to type the link manually because its an image:

(with all resolutions and 32 bits depth checked)

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Then you have to save the file somewhere on your Computer. After that right click on your Valorant desktop icon, go to Properties → Change Icon... → Brwose... and select the Valorant.ico file. Just click on apply and you are done.

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Note: If you delete the ICO file from your PC the game icon will also disappear.

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