From what I have seen in the past, it got de-registered
sometime before 1986 (my earliest microfiche), most
likely due to failure to return the trienial report
(that was a major sin against humanity and the FAA
back then!).

Failure to respond now, or bounced addresses, will get your N-number
suspended also. This happened earlier this year. I notified more than
one pilot to contact the FAA when the N-number list and deadline came
out.

Frank Whiteley