how to reset a raid

hi everyone i want to change the raid
set raid 10 (heroic) to set raid 25 ( heroic)
if anyone know about the macro i appreciate?
thank for your answers

first, you left the raid and go out of the instance.

then you make a neq raid group with 25 members and then you enter the instance agian ;)

even right klick on youre portrait and then look what options are there ( you must be the boss of the raid )