How do you get rid of old yellow script gear?

[Jojoya]

I wonder if it's something they forgot to activate. I think it's normally just really new gear that can't be desynthesised?

Might be worth submitting a bug report.

Someone had mentioned in a thread a while back that desynthesis was disabled on that scrip gear because it was getting abused by RMT bots in some fashion. I don't know the truth of it but considering all this time has passed without SE changing it despite multiple reports, it may be true.