SWITCHING OFF DISCRETE GRAPHICS IN LINUX MINT

hello everyone!,

i am having issue switching off the discrete NVIDIA graphics card in mint .
previously i was using elementary-os and i could switch off the power to
discrete graphics card by :

 echo OFF > /sys/kernel/debug/vgaswitcheroo/switch.

but this isn't working in case of MINT :

cat   /sys/kernel/debug/vgaswitcheroo/switch :

IGD(integrated graphics) : pwr
DIS(discrete graphics) : Dyn-pwr
DIS-Audio : pwr

even if i issue the command  there's no change . the power doesn't turn off.

Also there was no DIS-Audio in elementary-OS and DIS only showed "pwr"
instead of "DYN-pwr".