Basic Removal

All of these use remove, which takes the item out of the game completely: creative tabs, recipe viewers, recipes, tags, loot, trades, and inventories.

Remove specific items

{
  "action": "remove",
  "items": ["minecraft:tnt", "minecraft:bedrock"]
}

Remove a whole mod

{
  "action": "remove",
  "mod": ["farmersdelight"]
}

Remove everything in a tag

Every log, from every mod:

{
  "action": "remove",
  "items": ["#minecraft:logs"]
}

Remove every sword

Matches any ID ending in _sword, from any mod:

{
  "action": "remove",
  "patterns": ["/.*_sword/"]
}

Remove every spawn egg

{
  "action": "remove",
  "patterns": ["/.*_spawn_egg/"]
}

Remove only vanilla swords

mod limits the pattern to Minecraft, so minecraft:diamond_sword is removed but othermod:copper_sword stays:

{
  "action": "remove",
  "mod": ["minecraft"],
  "patterns": ["/.*_sword/"]
}

Remove a mod, but keep one item

Removes everything from AE2 except Certus Quartz:

{
  "action": "remove",
  "mod": ["ae2"],
  "not": {
    "items": ["ae2:certus_quartz_crystal"]
  }
}

Remove an item and fix the recipes that used it

Diamonds are removed, and every recipe that needed a diamond now needs an emerald:

{
  "action": "remove",
  "items": ["minecraft:diamond"],
  "replace_with": "minecraft:emerald"
}

Swap an item for a weaker version (1.21+)

Netherite Swords become half-broken Diamond Swords with no enchantments. Uses the same syntax as /give:

{
  "action": "remove",
  "items": ["minecraft:netherite_sword"],
  "replace_with": "minecraft:diamond_sword[damage=500,!enchantments]"
}

Remove fluids

Hides water and lava from recipe viewers:

{
  "action": "remove",
  "fluids": ["minecraft:water", "minecraft:lava"]
}