I am using FireBreath in MAC OS X Snow Leopard.
I have a plugin which is loaded in a webpage where User do some task invoking this plugin, however I wanna unload the plugin just when user is redirected to another page where the plugin it is not used anymore.
How can I destroy the instance of this plugin?
You can destroy the instance of the plugin simply by removing the object tag from the page; note that this will only destroy the instance, it will not unload the actual plugin module / shared library. There is no way to force the browser to completely unload the plugin short of restarting the browser.
Also note that when you browse away from a page with an object tag in it the plugin instance will be destroyed, so you don't actually need to do anything if the user is redirected to another page because the object tag will no longer be there.