Attwood water heater drain plugged

Never heard of an anode with a wire in it. Anodes are designed to deteriorate, instead of more important metal parts. You might have a hotrod or similar installed. In any event, I'd spray it with penetrating oil then use a reverse thread drill bit and drill to drill a hole. With luck, it'll come on out, if not, get after it with an EZ Out.
Worst case, drill it out until the metal of the rod is thin enough to collapse and pick out of the threaded hole. Chase the drain threads and insert a new plug/anode.

I tried some CLR and left it for awhile but no luck.

Drill it out carefully so you don't bugger the threads.

Shoot some vinegar in the hole to see if it will loosen the deposits? Just a thought.