Usually, if we want to disable Adobe Flash, then one has to navigate to the Add-ons page and wait for the Adobe Flash Player to load. Once you see all the add-ons loaded completely, then switch to plugins and look for Adobe Flash Player, and click on the enable or disable option to turn that plugin on/off.
QuickJava addon for Firefox
QuickJava in just few click lets you disable all those Adobe Flash, Java and Silverlight add-ons running in your Firefox browser and make your Firefox browser feel light. The add-on adds rigorous security settings and smart habits that lessens the chance of malware infecting your computer.
You can install QuickJava from the Mozilla extensions webpage and restart the browser to activate the plugin.
If a user wants to add few other shortcut buttons that should appear along with JS, Java and Flash. Hence to do that a right-click on QJ icon > Option. It will open a panel from where you can pick the desired plugin to add.
It offers better control over issues arising from plugin crash and script errors since users can disable those plugin when not using it and can also free up the memory being consumed by such addons.
There is also a proxy button in QuickJava which is hidden by default, but users can enable/disable it according to their need. It is available in the Mozilla Firefox add-on repository and can be downloaded for free.
If you want a more permanent solution, have a look at these posts: