You cannot alter a materialized query or staging table, but you can drop it. All indexes, primary keys, foreign keys, and check constraints referencing the table are dropped. All views and triggers that reference the table are made inoperative. All packages depending on any object dropped or marked inoperative will be invalidated.
DROP TABLE <table_name>
DROP TABLE XT
A materialized query table might be explicitly dropped with the DROP TABLE statement, or it might be dropped implicitly if any of the underlying tables are dropped.
A staging table might be explicitly dropped with the DROP TABLE statement, or it might be dropped implicitly when its associated materialized query table is dropped.