I just started using this mod, so I don't know if this feature ever worked. According to the wiki, this should be possible:

"incontrol kill: kill all entities of a given type. Possible types are: 'all', 'hostile', 'passive', or 'entity'. It is also possible to give the name of an entity instead of a type (like 'minecraft:enderman')."

I haven't been able to get this to work. I have tried these commands:

incontrol kill minecraft:creeper
RESULT: Expected whitespace to end one argument, but found trailing data at position 25

incontrol kill 'minecraft:creeper'
RESULT: Expected whitespace to end one argument, but found trailing data at position 16

incontrol kill "minecraft:creeper"
RESULT: Expected whitespace to end one argument, but found trailing data at position 16

incontrol kill minecraft creeper
RESULT: Incorrect argument for command at position 26

incontrol kill minecraft.creeper
RESULT: 0 entities killed

incontrol kill creeper
RESULT: 0 entities killed

Minecraft 1.21.1
Mod: 10.1.2 (NeoForge)