Delisted cards

I try to trade em to make sets craft the badges then convert the items i get into gems.

There are a few Steam Groups that are dedicated to just this "non-marketable Steam items"

Here is one such group:
http://steamcommunity.com/groups/deaditems

People do trade them. I, for eg, am not interested in gems, so I try to make badges of them.

There are some "dedicated" steam users that even have rules prepared - like 1:1 in same set, or 1:2 for any unmarketable card etc - it varies, but usuall you're the one that have to give more :/
If you have too many cards of same set, you can even use trade bot (theres quite a lot people using them for instant trade, sadly it only works in same set).
But if you prefer gems you should still look for guys collecting unmarketable cards - some of them will give you bit more gems than steam gives.

Easiest way to find them is to look up trade forums of unmaretable games (you know, badge site, next to missing cards, you have button to check up trades), on one of them you should find post made by a guy that collect/trade unmarketables (and list of trading bots was somewhere here, on steamgifts forum, just google something like "trade bot list steamgift" and you should find it).

If you don't want either badge nor gems, you can try to trade it for marketable items, but for that you should make your own posts on nonmarketable games forum and hope you will find someone that is willing to trade (probably you will have to waaaaait).

As to booster packs, maybe you should remove those games from your library (since steam gives you packs from games from your library). I never tried to remove game from steam, but i heard that it's possible now.

"after finding the option in the Help menu. Here are the steps.

Select "Help"

Select "Steam Support"

Select "Games, Software, etc."

Select that game

Select "I want to permanently remove this game from my account"

Select "Ok, remove the listed games from my account permanently""

VanillaBot accept same-set even cross-set 1:1 trades for non-marketable cards plus same-set 1:1 trades for non-marketable emotes and backgrounds.