With the release of the stable versions, we are able to retire the nl2015, de2015, and dk2015 from etsource.

@mabijkerk proposed the following process to achieve this:

1. Release the stable vesion
2. Delete the dataset from #latest
3. Migrate the scenarios for those datasets to 2025-01
4. Communicate removal.

Will pick this up with @noracato & @louispt1