adb to disable the very first selection for yangqi desktop.

adb shell cmd shortcut get-default-launcher
Launcher: ComponentInfo{com.mitv.tvhome/com.mitv.tvhome.MainActivityUserMode}
Success

adb shell pm set-home-activity "com.yangqi.rom.launcher.free/com.lerad.launcher.home.MainActivity"
Success

adb shell cmd shortcut get-default-launcher
Launcher: ComponentInfo{com.yangqi.rom.launcher.free/com.lerad.launcher.home.MainActivity}
Success

then disable the mitv, not delete it. 
after test, also can not disable it. will cause black out.
adb shell pm disable-user --user 0 com.mitv.tvhome
Package com.mitv.tvhome new state: disabled-user

Also, the command is failed or cannot be executed :
adb shell pm disable com.mitv.tvhome/.MainActivityUserMode