How to properly delete a game steam no longer lists?

[Eon]

So occasionally, I've played games on steam. They then get removed from library and/or store, or I purchase them....or in the past, I'd do them on free trial/weekend, weekend would end...and now it's still installed but I can't see it in library or find an easy way to uninstall it.

So my question is this; how do I double check which folders for demos/games n what not are not showing up in steam library, beyond comparing every folder found to the games in steam?
And when deleting them outside of steam....beyond the folder, what else do I have to delete that may be tied to the game? I remember there isn't be a file for each game in one of steam's folders that it needed as well as its folder to run...are those gone? Am I misrememering/forgetting something?

I mostly ask cause I never got around to uninstalling Age of Empires Online before it was shut down so...before I delete the folder, I wanna be sure there's nothing I can/should do in steam (it already doesnt show in library not even like how order of war showed itself as unowned but installed after it was shut down) or anything else outside of the folder I need to delete in relation to it.

[Starscre4M]

If you have a game that got removed from Steam it should still show up in your library, even if it is uninstalled, in case of free weekends it should also show up as "pre-loaded"...

Anyway you can use this site to see what games you have that you can't buy on Steam anymore:
http://timekillerz.eu/removed/tools.php?steamprofile=76561197998010827

In your case it says:

• Deus Ex: Human Revolution
  
• Deus Ex: Human Revolution - The Missing Link
  
• DiRT 2
  
• Dragon Age II
  
• Droplitz
  
• Fable III
  
• Gotham City Impostors
  
• Infernal
  
• James Cameron’s Avatar™: The Game
  
• Neverwinter Nights 2: Platinum
  
• Risk II
  
• Shellshock 2: Blood Trails
  
• The Chronicles of Riddick: Assault on Dark Athena
  
• Your Doodles Are Bugged!
  
• Zombie Driver

If you want to uninstall any of them, you should use the steam client, but if you can't or it says that it's already uninstalled, or for some weird reason it doesn't show up, you can delete the folder in Steam\steamapps\common, and no there isn't other files, it used to have .gcf and .ncf files in your steamapps folder, but since the steampipe update it's just the folder.
You could also try to go to the steam console steam://open/console and use the command:
app_uninstall "id of the game"
You can easily find an appid you want here: http://steamdb.info/apps/

[Eon]

Wait HR was removed? Oh right, Directors cut.
Forgot dirt 2 was removed.
And fable 3.
Avatar was removed? Huh didnt know that.
same with NWN2 Plat....and riddick...and doodles. ZD has HD, and Shellshock 2 was bad.
risk 2 to be fair has factions available in its place now which i wish I had instead lol

But yeah thanks. If its just straight up delete folders now, that's awesome. Totally didnt know GCFs were made irrelevant, and glad to know theres no other files or w/e to mess with. Cheers thanks for help. Will keep in mind for Age of Empires Online n other games in question.