How to remove icons showing question marks of deleted apps from Launchpad?

Solution 1:

[Worked] In Yosemite open Launchpad, hold down control key and click on icon you wish to remove. A question mark should appear over the icon. Just drag and drop to Trash.

Solution 2:

In my occasion all the shortcuts had the question marks on it, so I didn't have a use of CTRL+Click (and it didn't work). However as @user310633 mentioned, the Kill command as below worked.

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

PS: Sorry I had too create a new comment to add my experience as my reputation score on this forum doesn't let me answer on previous comments.

Solution 3:

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