Steam has a 'trading card'-social-media thing. I don't really get it, and I have zero interest in it.
As far as I can tell, it basically serves to clutter up the Steam interface, and constantly barrage you about new junk in your 'Steam Inventory' that I frankly don't care about.
Is there anyway to disable the whole thing? Maybe I just hate (certain types) of fun, but I frankly completely fail to understand why I should care about the whole affair at all. It would make the steam client a lot nicer if I never had to see any of it again.
There doesn't seem to be any way to just delete cards from your steam inventory.
Best Answer
To piggyback on what @Nitrous Oxide (Awesome name) Said... You cannot stop/turn off the Steam Trading Card system. They are earned by playing games you have that has the Trading Card System enabled and random events.
I understand it can be quite frustrating at times to receive two-four cards at once and have to view-acknowledge them in order to make the notification disappear BUT you could simply ignore the entire system and horde cards for some time. Eventually you could trade in sets of them for new quirky badges, backgrounds, and experience for your Steam Profile. OR you could "bite the bullet" and enter the Trading Card community once a month or so and sell all the cards you have for pennies on the dollar to eventually be able to buy something you want.
I hope this helps out a bit.