How do you remove non-App Store apps that are not in Applications from Launchpad?

Hi, this is my first post to the Apple forums...
So, I use the Steam game app a lot to manage my different games on my computer. Recently, I cleaned out the games I no longer wanted or had lost interest in, and all of their files, INCLUDING the .app files stored in Application Support, were successfully deleted. But, Steam also automatically adds app shortcuts to the Launchpad when you download a game, which is an option I always left checked during the download process- because why not, right?

The problem is that now, even after completely deleting ALL TRACE of these apps, they remain on my Launchpad. Just keeping them there isn't a solution; as a very neat, organized person, it would annoy me to the end of time to have random apps on my Launchpad that don't do anything. And since these apps aren't from the App store, they don't have an (X) in the upper left hand corner when you hold down on them.

I don't know tons about Macs, but after a quick scan of things online people have recommended deleting all the files for your Dock under Application Support, because apparently Launchpad is based on your dock. But that doesn't sound right to me. I thought Launchpad was based on Applications? Again, I'm more savvy with Windows but I just got this thing a year ago so I'm doing what I can.

On a side note, these game applications were stored in a folder titled "Games", which was originally identical within both Applications and Launchpad. Once I began deleting apps from the folder in Applications, however, they got stuck in the folder within Launchpad.

I also cannot move Game Center out of the folder in Launchpad, and when I do so it says "This app cannot be modified/deleted", even though I originally had Game Center outside of the folder.

Computer specs:

MacBook Pro 15 Inch (mid 2009)

Running OS X Yosemite (10.10.1) [I updated just last night, I had been running 10.9 before and still had this problem]

Processor: 2.8 GHz Intel Core 2 Duo

Memory: 4 GB 1067 MHz DDR3

Graphics: NVIDIA GeForce 9600M GT 512 MB