Cannot turn off heartbeat LED in Ubuntu 21.10

I tried using the directions in the manual and it does not work.
Any suggestions?

root@Khadas:~# /sys/class/leds/sys_led# echo none > trigger
-bash: /sys/class/leds/sys_led#: No such file or directory

Here is the contents of that file:
none rc-feedback kbd-scrolllock kbd-numlock kbd-capslock kbd-kanalock kbd-shiftlock kbd-altgrlock kbd-ctrllock kbd-altlock kbd-shiftllock kbd-shiftrlock kbd-ctrlllock kbd-ctrlrlock timer oneshot [heartbeat] backlight gpio cpu0 cpu1 cpu2 cpu3 cpu4 cpu5 default-on transient panic rc_feedback emmc sd sdio rfkill0 rfkill1 rfkill2 rfkill3

We don’t release any Ubuntu 21.10 images.Which image you used? And what’s the kernel version?

fred@Khadas:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 21.10
Release: 21.10
Codename: impish
fred@Khadas:~$ lsb_release -r
Release: 21.10
fred@Khadas:~$ uname -r
fred@Khadas:~$ uname -a
Linux Khadas 4.9.241 #24 SMP PREEMPT Sat Jan 8 13:20:29 CST 2022 aarch64 aarch64 aarch64 GNU/Linux

Sorry for posting this.

It was my mistake caused by me not carefully reading the code.

FYI this might help some one else.

root@Khadas:~# cd /sys/class/leds/sys_led
root@Khadas:/sys/class/leds/sys_led# echo none > trigger

It works fine per your user manual, my apologies.