While all the suggestions would work, there is a better way. While
chemicals would seem easy yet take longer, there are concerns as to
your health and well being of your body. Acetone if it is used often
with no gloves to protect your hands can break down the tissues
(fatty portions of molecules) in your hands. Better to not use it if
there is an alternative. Other chemicals in the same ilk can do just
as much damage or worse.
Using a gentle flame on such a small piece would take it up to high
and could compromise things. “Notice I said could, not would” The
easiest way and quickest is to get a good heat gun. It;s not a hair
dryer, but a good tool sold at Home Depot or the like. It has a much
higher heat than a hair dryer. It is what is used to melt epoxies.
How do I know this? My husband bless his heart sent me to Austin
Texas to learn to make custom golf clubs. He would have gone, but he
doesn’t do well with things that don’t have a keyboard. It’s a wonder
I have 2 kids. Anyway, they taught us how to melt the epoxy used in
making golf clubs. It doesn’t take long on really large items. It
also doesn’t take the temp up to the point that it would anneal the
tube you have. Best of all you get a new tool for your work. It gets
hot enough to do some of the metal clays on the market. My words of
wisdom, wear gloves, and put the heat gun into a vise so you have
both hands free.
Now once the epoxy is melted, just use a smaller bit of wire to push
the mess out.