Before you drop a dbspace, you must first drop all databases and tables that you previously created in that dbspace. You cannot drop the root dbspace.
Before you drop a blobspace, you must drop all tables that have a TEXT or BYTE column that references the blobspace.
Execute oncheck -pe to verify that no tables or log files reside in the dbspace or blobspace.
Before you drop an sbspace, you must drop all tables that have a CLOB or BLOB column that reference objects that are stored in the sbspace. For sbspaces, you need not delete columns that point to an sbspace, but these columns must be null; that is, all smart large objects must be deallocated from the sbspace.