We are aware of this issue and it is on our roadmap:

https://support.mixo.dj/t/remove-deleted-playlists-from-export-popup

I've subscribed you to the idea so that you'll be notified when there is an update

there is an error occur according to this figure that when i gonna export the playlist to Traktor i saw there are many playlist that i have deleted still show as the export options. i didn't test other software export.