Hello, how're you?
I have been working for a lower league team, on their image, I have remade their logo and social media so they have they can have a nice representation online and in person. Their logo was been a picture of a logo draw on a paper since the foundation. 

I want to update the active logo in the source data but I can't. Can someone help me please?

Little bit confused?

Do you mean you work for the club in real life and you've redesigned their badge? Or is this something you've done (i.e. a fantasy badge) for the lower league club to appear in-game?

If it's the first, then it'd just be a matter of submitting the updated logo as a source to whatever logo pack (probably via the logo pack's website if they're not connected through this site (which will also be the same for the fantasy badge too)

If you mean how do you get your drawing into your own game, you'd need to re-do it using something like Canva or Photoshop and generate the files that way or at the very least scan it and make sure it's in the appropriate format and size. 

dm me discord @seloriste

first one, already submitted the logo as the source one, but the active logo is the older one.

In that case, PM the creator of the logo pack. You may have to wait until the next update for them to release the new logo version.

How do I know the creator?

It will typically be the person who created the post. I don't use ESS Logos specifically, but for the logos I do use there'll either be a forum post or you can contact the uploader.