How to make an empty Minecraft world?

If you go in peaceful mode in settings you will not get monsters. To remove cows and stuff, make the top layer any block other than grass or dirt and they shouldn't spawn. If they still do make it halfslabs (Not sure for grass but sure for the slab one)

When you first click on create new world, click on the option "more world options…" From there you will see the option "World Type: Default" Click that until you see the option "Superflat". The click Create new world. Then go back into your options and where it says "Difficulty" set it to peaceful. And there's the world you requested.

Have fun and Happy Crafting!

Use the command /gamerule doMobSpawning after creating the superflat world. It will prevent all mobs from spawning.

If you're playing on the PC version, go to your server properties document (it will be a PROPERTIES file) and change the value for "Spawn Animals" to False. If you're playing on Peaceful, you won't have to worry about monsters and the like spawning, but if you plan on playing on some other difficulty, change the value for Spawn Monsters to False. For the Superflat landscape, when you first create the map, select the option to make the landscape super flat.

Again, this response is for if you're playing on the PC version.

First, set your difficulty to peaceful by going to the options menu, this should get rid of the monsters, then create a super flat world, or a regular one, it doesn't matter and when you generate the world do "/gamerule doMobSpawning false" in the chat and without quotes, that'll make it just "you and the blocks"