How to remount vendor partition as R/W in Android 10 device

How to remount vendor partition as R/W in Android 10 device

when adb remount is not useful for this use case!!
STEPS

$ adb root
$ adb disable-verity
$ adb reboot && adb wait-for-device
$ abd root
$ adb shell mount -o rw,remount /vendor/firmware_mnt

(be careful! NOT add slash in the end of path)
FEEL free to modify its content from now on
$ adb shell mv /vendor/firmware_mnt/image/qca6390 /tmp/
$ adb shell sync