If the account is closed, they may delete the entire TL instead of just the baddie if they choose. In this case, you have to decide if you can live with the TL gone for your average credit age.
Current FICO8: EQ:782, TU:754, EX:767 | 1x 30 day late 6yrs ago AAoA: 10 years; AAoOA: 13 months; Credit Length: 21 years INQ Eq: 3 / Tu: 5 (4 for auto) / Ex: 9 (5 for auto)
I also have late(s) on CapOne. Mine are from 4/02 and 6/02. One is 30 days and the other 90 days. To date, I'm still sending GWs, but come January, I will stop out of fear it will get deleted. It is older than my avg. age by 3+ years.