Developed by Hyyan, Flexible Widget Title is a new plugin that enables users to hide widget titles from the frontend of WordPress. When activated, apply brackets to the titles you want to hide. For example, [A Text Widget Title].
Although the same effect can be accomplished by leaving the title field blank, it makes administering several text widgets in the backend of WordPress more difficult. This plugin allows you to keep the titles in the backend for easier administration but still be able to hide them on the frontend.
I tested the plugin on WordPress 4.0 and didn’t experience any issues.
Or you could use my 3 year old Remove Widget Titles plugin! :)