Delete data of interrupted import site

I have a site (id=x) which I removed from the panel but its data is still in the database and every time I run the core:archive command the script says it still needs to be completed. How can I remove all its data (and all temp unused data) from the database?
I don’t want to remove any used data… just the temporary import data and unused data from the database.

Unfortunately this is not implemented yet, in order to keep the data in case of erroneous delete. Though feel free to create a feature request for this as it would be very useful indeed.