What is the best way to restrict a user's access to software. Essentially, I want to lock down an account to have access to just a handful of apps. I especially want to restrict access to the Software Station and Update Station.
I am enjoying GhostBSD so far but the user administration is not what I am used to.

Thanks in advance!

I‘d suggest to look at docs.freebsd.org how to manage users and groups.

Would Start here:

https://docs.freebsd.org/en/books/handb ... ermissions

Chapter 3.3.3 „Managing Groups“.