Hey there. There are several ways to do this. You can use an application like clicktoflash (http://clicktoflash.com/) or you can simply disable plugins in safari or firefox.
Firefox allows you to disable a particular plug in like flash. Safari allows you to block all plugins. I blocked all plugins on safari to make that my browser for travelling where i dont need to access flash content so much. Clicktoflash is basically just a front end for manually disabling flash.