Yeah, worry about the wire and lug but sacrifice the glow plug. Take a sharp chisel and a hammer and chop it off. The threaded electrode is soft iron and can be cut easily with a chisel.

Edit: when you install the new glow plug, use anti seize on the threads and do not over tighten. It's an electrical connection, not mechanical so a little beyond finger tight with a wrench so the nut does not come loose is sufficient.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked