Update: As of forge build 1.16.4-35.1.32, forge fixes the vanilla bug mentioned below via a forge patch.

As of this forge build, dimensions can now be safely removed from a server without unregistering them via Dimension Scalpel or similar tools. The below description will be left intact for historical purposes.

In 1.16.4, data-driven worldgen makes it very easy to add custom dimensions. However, removing dimensions is slightly trickier.

If a mod or datapack that adds a dimension is added to a server, and then removed, this bug occurs, preventing the server from recognizing the nether and end dimensions:
https://bugs.mojang.com/browse/MC-197860

Dimension Scalpel adds several commands to work around this bug, including:
* Remove custom dimensions from the dimension registry (without triggering the MC-197860 bug), allowing the mod or datapack that added the dimension to be removed from the server
* Restore a dimension registry that has been corrupted by the MC-197860 bug

Further documentation and guidelines on using the available commands is available via the wiki link above.

This mod is 100% server-sided, it does not need to be installed on clients unless the user desires to use it in a singleplayer world or in a LAN world they are hosting.

Be aware that while using Dimension Scalpel with databack-based dimensions is generally safe, using Dimension Scalpel with other mods that add or work with dimensions may cause strange behavior due to unforseen interactions.

Always ensure your server's save data is backed up before using Dimension Scalpel.