How to switch my gamemode back to survival?

On minecraft.
i switched my gamemode from survival to creative using the LAN method since i disabled cheats when i created the world and now i can't get it to switch back to survival. How can i change it back? I tried gamemode/ 0 and all those commands.

Watch tutorials on NBT Explorer… That program can enable/disable cheats. Just watch tutorials and learn about NBT Explorer.

https://www.mediafire.com/?fjs5rpqddpvpqd3 Download this.

Enable cheats again. That is the only thing I can think of.