How to delete RDD with unpersist

I'm trying to understand how RDD.unpersist() works but I'm running into some confusing output.

When I force-delete an RDD and then try to show it:

rdd.unpersist(blocking=True)
rdd.show() # why doesn't this line throw an error?

I expect the second line to error, but it doesn't. The RDD prints out as usual.

I saw these two questions: Why doesnt spark unload memory even with unpersist, How to make sure my DataFrame frees its memory?. They were both helpful in understanding how to use unpersist but don't answer my question.

I'm using a Jupyter notebook and wondered if the notebook might be caching the RDD, so I tested this out in a .py file as well, and the same thing happened.

If the RDD has been deleted, why does it print when show() is called on it?

If it hasn't been deleted, how can I delete it?

You can check the rdd is cached or not by using the attribute is_cached.

rdd = sc.parallelize([1, 2, 3])
print(rdd.is_cached)
rdd.cache()
print(rdd.is_cached)
rdd.unpersist()
print(rdd.is_cached)
rdd.count() -- ignore response
print(rdd.is_cached)

False
True
False
False

Without cache call, the rdd is not cached and unpersist is not working as you expected. It will not delete rdd itself, just remove cached version. How do you delete a variable?