@kanarokan If you're requesting a source, there's no need to remove the background yourself, please just leave them in their original state 👍

Also for transfermarkt they resize all images to 300x390, sometimes the original is bigger and sometimes smaller, even if it is smaller it is better to get it that way

1) Go to the player's/staff's profile, click the profile image to view a larger image, and open that in a new tab.
2) You'll get something like this URL: https://img.a.transfermarkt.technology/portrait/big/435648-1576766482.jpg?lm=1
3) Copy this part of the image URL, the rest doesn't matter. https://img.a.transfermarkt.technology/portrait/big/435648-1576766482.jpg?lm=1

4)  Then paste that part of the URL at the end of this URL: https://tmssl.akamaized.net/images/portrait/originals/

Like so: https://tmssl.akamaized.net/images/portrait/originals/435648-1576766482.jpg

Now you can get the actual full-size image instead of one that's resized to 390px tall.