I mistakenly allowed the "Helper Tool" to install, thinking it was necessary for Java's install
Rumor has it it's bloatware, or adware, and that it's not needed for Java.
The above is incorrect. The helper tool is required and is an application used to install Java.
How does one find and uninstall this "Helper Tool"?
You don't need to. See above.
For the past couple of releases, Oracle has used a standard installer package to install Java 8. With the release of Java 8 Update 65 though, Oracle returned to using an application to install Java.
Oracle’s Java 8 Update 65 install application has the following behavior:
This application will prompt for admin privileges before fully
launching.
Once you provide admin authentication, the application launches.
Source Oracles Java 8 Update 65 – The return of the Java install application