Update: SQLite 2021-03-12 (3.35.0) now supports DROP COLUMN.
From: http://www.sqlite.org/faq.html:
(11) How do I add or delete columns from an existing table in SQLite.
SQLite has limited ALTER TABLE support that you can use to add a
column to the end of a table or to change the name of a table. If you
want to make more complex changes in the structure of a table, you
will have to recreate the table. You can save existing data to a
temporary table, drop the old table, create the new table, then copy
the data back in from the temporary table.For example, suppose you have a table named “t1” with columns names
“a”, “b”, and “c” and that you want to delete column “c” from this
table. The following steps illustrate how this could be done:BEGIN TRANSACTION; CREATE TEMPORARY TABLE t1_backup(a,b); INSERT INTO t1_backup SELECT a,b FROM t1; DROP TABLE t1; CREATE TABLE t1(a,b); INSERT INTO t1 SELECT a,b FROM t1_backup; DROP TABLE t1_backup; COMMIT;