How to remove the light bulb in PHPStorm?

Actually, you CAN disable the bulb in v6. Settings (or Preferences on Mac)-> Intentions then uncheck the appropriate group. Poof. No more lightbulb getting in the way.

Settings/Preferences | Editor | General | Appearance | Show intention bulb

Please note that hiding bulb and disabling intentions (as accepted answer suggests) are different things.

Yes, you may end up with hidden bulb in both cases but this way (in this answer) you can still invoke those useful intentions via keyboard shortcut (typically Alt + Enter) while in other case they will be simply unavailable.