removing data from config.yml

How can I remove data from config.yml for a certain player?

say it looks like this:

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toolinv:
ab407223-1c1e-42c9-a61a-daa722d8cdcb:
a:
type: DIAMOND_PICKAXE
enchants: []
durability: 0
amount: 1
b:
type: DIAMOND_SHOVEL
enchants: []
durability: 0
amount: 1

but I want it to look like this:

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toolinv:
ab407223-1c1e-42c9-a61a-daa722d8cdcb:
a:
type: DIAMOND_PICKAXE
enchants: []
durability: 0
amount: 1

 

@thechrisanator
config#set("path.to.stuff.to.remove" , null);

Does not have to be the exact object. If you wanted to delete everything under b, you would just need to set that config section to null.

 

so..

getConfig().set("toolinv." + event.getPlayer().getUniqueId() + ".", null);

that?
because that just makes this error:

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Code:

org.bukkit.event.EventException: null
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot.jar:git-Spigot-e8ded36-acbc348]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-e8ded36-acbc348]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:500) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:485) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.PlayerList.disconnect(PlayerList.java:405) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1106) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.NetworkManager.handleDisconnection(NetworkManager.java:321) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.ServerConnection.c(ServerConnection.java:174) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:845) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [spigot.jar:git-Spigot-e8ded36-acbc348]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_191]
Caused by: java.lang.IllegalArgumentException: Cannot set to an empty path
        at org.apache.commons.lang.Validate.notEmpty(Validate.java:321) ~[spigot.jar:git-Spigot-e8ded36-acbc348]
        at org.bukkit.configuration.MemorySection.set(MemorySection.java:168) ~[spigot.jar:git-Spigot-e8ded36-acbc348]
        at org.bukkit.configuration.MemorySection.set(MemorySection.java:202) ~[spigot.jar:git-Spigot-e8ded36-acbc348]
        at me.Darkolythe.Multitool.main.onPlayerLeave(main.java:58) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_191]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_191]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_191]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_191]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot.jar:git-Spigot-e8ded36-acbc348]
        ... 12 more