CMDBuild ensures the complete versioning of all changes to all data.
So you can not delete physically data of any kind, including lookup lists, otherwise it would not be possible to decode cards linked to other data.
To avoid that CMDBuild displays lookups you do not need, however, you can set the lookup status as non active.
CMDBuild Team
You're doing it at your own risk.
Log in to the database, hit query
truncate "Lookup";
and then press enter.
Restart tomcat and postgresql if necessary.
Oh fairly easy ;) (i've done this quite a few times myself when modelling my database)
Open PgAdmin or any other tool
Go to the LookUp table, view data
Delete the records with Type = $yourlookup
However the classes that use $yourlookup will be crippled and sadly you cannot delete attributes when there is data in your tables.
But you could try the following (note that i haven't done it myself yet and MAKE BACKUPS!!! ):
Change the ordering of your attributes in the class where your lookup is defined and all subclasses and move it to the lowest position
Delete the column in PgAdmin
clear the cacheand or restart