I’m going to give livestream tomorrow (Walksnail HD) but the thing is when i hdmi out all osd elements are visible on the screen 
Betaflight has switch to turn off osd but i’m using ardupilot
Any idea how to do it with radio by switch instead of connecting to via usb and turn osd off?
Oh stressful.
Yes, I think there is an easy way to turn the OSD off from the display.
Have a look here OSD wiki
Basically set up a on/off switch on your radio tx and set the OSD_CHAN parameter to that channel on your FC.
. keep the OSD_SW_METHOD to default, 0 for simplicity
. your OSD1_ENABLE is probably already set to 1, enabled, so just set OSD2_ENABLE also to 1, enable. Then you clear that screen from all fields (no other OSD2_ things enabled). Can be done in mission planner, under Config and then under OSD.
The result is when you flip the switch in any direction the screen will change to normal OSD or a blank screen.
good luck!
problem solved, thank you so much