How do I uninstall the Java JDK in macOS?

You can get official oracle instruction to remove java from macOS here

In your macOS terminal type this one by one

sudo rm -fr /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin 
sudo rm -fr /Library/PreferencePanes/JavaControlPanel.prefPane 
sudo rm -fr ~/Library/Application\ Support/Oracle/Java

After that you can navigate to specific version of java that you intend to delete by using the following command:

cd /Library/Java/JavaVirtualMachines

Then type ls in your terminal to list down all the Java Virtual Machine Folders.
Finally add the version number you want to delete like this

sudo rm -rf jdk-10.0.1.jdk

Instead of jdk-10.0.1.jdk you can give any version number which are listed down in your above mentioned folder.

Update:

1. First remove the java runtime

   $ sudo mv /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin ~/
   $ sudo mv /Library/PreferencePanes/JavaControlPanel.prefpane ~/
   

   Now you can close and reopen the System Preferences window to see that the icon is gone.

2. Next, uninstall the Java JDK. Open a terminal and change to the Java directory:

   $ cd /Library/Java/JavaVirtualMachines
   

   You can use ls at the prompt to see what is in the directory and copy the jdk's path name with version number that you wish to delete.

   $ ls --directory *jdk*
   examplejdk-7.jdk
   

   Copy the exact name of the path you want to remove -- for this example it's examplejdk-7.jdk. Next, use that path name inside of single quotes ('examplejdk-7.jdk') to move it to your desktop. Instead of deleting the directory, this moves it to your desktop so you can restore it later in case there's an issue!

   $ sudo mv 'examplejdk-7.jdk' ~/
   

3. To confirm that it has been removed, run this command:

   $ java
   

   This should output an error message:

   No Java runtime present, requesting install