Actually, one resource that I would possibly recommend checking out as an intro to these realms is the Landmark Forum course.

I wouldn’t say it’s about “unlearning beliefs,” though a different means towards similar ends.

Most people who go through it give rave reviews, and I do personally feel it was one of the most notable entrance points on my own path, an investment which would be difficult to not reap worthwhile returns.

They have centers in hundreds of major cities worldwide, so is very accessible as well.

The Advanced Course is also excellent. There are a number of different organizations that offer similar programs, though these have stood the test of time and evolved nicely, retaining a format that works.
;-)