All I can see is a kick button, which temporarily blocks them from rejoining, but does not completely ban them. I tried /ban but the command does not seem to exist. How do I accomplish this?
Edit: Can you whitelist and theoretically “ban” someone on Minecraft Realms?
An anonymous user has suggested this new method, which sadly I can't give credit for because they are anonymous, but it's a better idea.
Have a repeating always active command block with:
/kick @a[tag=banned]
You can then run this command to "ban" them:
/tag A_USERNAME add banned
To unban someone:
/tag A_USERNAME remove banned
A workaround way to do this without the whitelist is to have a repeating always active command block with:
/tp @a[tag=banned] 0 253 0 facing 0 255 0
Make sure the chunk at 0, 0 has been generated or use a different (X, Y)!
You can then run this command to "ban" them:
/tag A_USERNAME add banned
To unban someone:
/tag A_USERNAME remove banned
This method works by repeatedly teleporting the banned player high in the sky. This makes it impossible to do anything (assuming they're not hacking), as they will also be facing upward.
Sadly you can only ban or unban someone if they are online though (Once they are banned though if they leave and join they will still be banned).
There is unfortunately no way to ban players currently, but there is a way to whitelist, so if you only want some people to be allowed on you can turn the whitelist on and add the players you want to the whitelist.
All you have to do is use:
/kick (player you want to kick) (reason for kick)
and put it in an always active repeating command block. If the player tries to join the world, they will be met with whatever message you used instead of joining your world. To unban them, just remove the command block. They should be able to join. Unfortunately, the person CAN just create new alts, and there is no way around this as of right now.
This was previously a suggestion to the marked answer, but the suggestion was rejected as it was "intended to address the author of the post and makes no sense as an edit." As such, the following answer is a paste of the suggestion I've written up previously.
Create a repeating always-active command block. Keep it empty for now, but ensure it exists so you can unban people at any given point of time. You can link together additional chain always-active command blocks if you have to unban multiple offline people at once.
Placed directly next to the command block and according to the direction the repeating command block is pointing to, have a chain always-active command block with:
/kick @a[tag=banned]
You can then run this command to "ban" them:
/tag A_USERNAME add banned
Note that this can also be placed in the one of the chain command blocks mentioned earlier, if you want to make sure someone is not welcome in your multiplayer world, regardless of if they have joined it.
To unban someone, go to one of your command blocks and type this in:
/tag A_USERNAME remove banned
When you can ensure the person you need to unban is unbanned, remove the command.
