Edit: There is also mention of ifconfig in the old forum. If you have more than one SSIDs available and only want to disable one of them then ifconfig wlan0 down would be helpful along with ifconfig wlan0 up command followed bt wifi command so all the changes take effect. Be sure to change it for your circumstances according to the Wi-Fi interface you want to disable.
Yes you are right, it can be easily executed but you still need cron to execute it. You would just replace the commands with the path to execute the script.
I am not sure if your cron tasks will still work because you put the commands wrongly there, it should be: 0 1 * * * /root/./wifi_off.sh because this is how you execute a script, with a leading ./. You may also need to give the script, execution permission with chmod +x /root/script_name or else it may not work.