If you do not want to use the gnome settings panel then nmcli can also achieve that.
Since you claim not to use NetworkManager you may have to locate the means you use to define the network connections and disable it with that tool.
I think the older ifconfig command has similar functions but have not tried that recently. It was mostly replaced by the NM tools.
You need to go into /etc/sysconfig/network-scripts/ and edit the file for the interface. This was the way before NM took over. If there isn’t a file, you’ll need to create one. I can’t find the old Fedora docs that would have had the info, but here’s the docs from Redhat on how to do it: