iMovie update stuck with phantom app

Question

when I updated iMovie back on July 7, I had an error where it kept continuously saying that I had an update, but what it kept doing was installing the same update over and over. At one point I had two iMovie updates going through with one installing and one downloading. Finally it quit, but I was now stuck with this phantom app that does not allow for me to get rid of. Holding option allows for the x to come up to delete, and you can make sure that you want to delete it, but after following the prompt it just sits there allowing for you to go through it again.

I am wondering if anyone knows how to get rid of this because it is quite annoying to just see it hanging there.

More info: Was on Mavericks when it happened, have moved to the 10.10 beta

Answer 1

So thank you to @GeorgeGarside for helping me understand where the problem would lie I was able to find an informative article on correcting the problem

1. Go to the Finder.
2. Hold down the Option key and click on the the Go menu.
3. Select Library.
4. Look for the Application Support folder. Open it.
5. Look for the Dock folder. Open it.
6. Locate files ending in ".db". Drag them into the Trash.
7. Go to the  menu and select Restart (or log out if preferred).
8. Click on the Restart button (or log out).

Source: http://www.imore.com/how-reset-launchpad-mavericks

Answer 2

Try resetting Launchpad's list of applications. Note this will also reset your layout including folders. Run the following command, then log out and back in.

defaults write com.apple.dock ResetLaunchPad -bool true && killall Finder

^{Source: http://www.amsys.co.uk/2013/blog/how-to-reset-os-x-launchpad/}