Solution imports are always additive - nothing is ever deleted when a solution is imported.
The reason deleting the column from the database wasn't successful is because CRM also maintains a set of tables which contain metadata describing the imported solutions.
I would suggest in this order:
- Restore your database to a good state if you can.
- Try and delete the fields from test via the CRM UI in the customisations section, you might get lucky if the field is non longer part of your managed solution.
- Uninstall the managed solution, you will loose any data but it should give you a fresh base.
- Contact Microsoft for support in case they have any wizardry they can apply at the database level.
- Try hacking the field out of the metadata (be sure to take a backup).
- Create a new test instance - its only a test environment after all and they are expendable for these reasons.