I would like to make a script and one of the important thing it's that it needs to connect by ssh to my openwrt.
My script worked perfect till I put a password to my user.
In my other linux device I wrote ssh User:Pass@192.168.1.2 and it worked but in Openwrt it didn't.
Putting passwords into a script is considered very bad form.
I'd first find out if there is a way to do what you need without a user login!
If you search on "using ssh key authentication" you will find out how to configure a "key" that establishes your identity to the ssh server. You'll still need to properly protect that key as it is "your signature".
If you use ssh, you should also look into binding a specific command to that key. For example, the key could be used only to run wifi reload and nothing else.
Is there any possibility that I could make a new user without any password?
when I've opend a new user I had to provide a password and even if I pressed enter and leave it blank it also requested password when I tried to connect.