I read here that in order to get stock openwrt on my GL-B1300 I should do the Uboot-web installation. Although here https://openwrt.org/toh/gl.inet/installation is says that GL-inet products can be flashed with a Normal upgrade in the "GL.Inet web interface to re-flash your device using OpenWrt".
Can someone point me what is the right direction for me to go?
yes. I saw that, but since there is the other page for gl.inet devices saying there is a "Normal installation" I wondered if this would be possible for the GL-B1300. It is not included in the commit message. So the answer is that I must flash using teh Uboot?
also in the advanced settings (luci) I have this option:
Flash new firmware image
Upload a sysupgrade-compatible image here to replace the running firmware. Check "Keep settings" to retain the current configuration (requires an OpenWrt compatible firmware image).
does it not work? I would like to know that it doesn't before trying it.
GL usually has Uboot with web-interface, so you can do what you want not touching first mtd partition. I recommend you to mtd write image into specific partition.
I only use Uboot for recovery and it works fine. You can use that one or you can flash OpenWrt straight from the GL interface.