MyBB Community Forums

Well I don"t know what it is called 

              But tell me how I can remove this flash panel from forum

Not flash, its called "Friendly Redirection Pages"

Go to Settings -> General Configuration -> Friendly Redirection Pages - > Set to off

You can also get users to turn the friendly redirect pages off themselves (if you want them on by default): User CP -> Edit Options -> Other Options -> Show friendly redirect pages.