How to reset Minecraft Demo timer without resetting the World – MacOS

Open up Finder and hit the Shift, Command, and “G” key simultaneously and then type in ~/Library/Application Support/minecraft/saves/Demo_World and hit return.

This should put you in your Demo World minecraft directory.

Now delete the “level.dat” and “level.dat_old” files and restart minecraft.  Your time should now be reset… As well as your Objectives.