Old old Romex type connectors

I have a house that was built in 1946. The electrical wiring is the 2 wire stuff covered in black braided material. I want to replace a utility box where a light fixture was and hang a ceiling fan. my question is, how do i get the old wiring connectors off the box? Do they just snap in or what? TIA
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Navin R. Johnson wrote:

We'll do better at helping you if you describe what the things you are calling "wiring connectors" are.
Are they on the ends of the wires, or do they surround the romex cable and clamp it in place to keep it from pulling out of the box?
Jeff
--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

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