Option 1: Delete the table and start over. On a development machine, this is no biggie. On a production system, this is NOT ADVISED. If you delete the table, you delete all the data in the table.

After deleting the table, you can start over.

mysql> drop table names;

Option 2. Alter the table. You can alter columns with possible data loss. For example, if you shorten a varchar(252) to a varchar(4), the database will truncate any data that is longer than 4 characters. If you change from a varchar(252) to an int, I have no idea what will happen, but probably nothing good.

mysql> alter table names modify lastName varchar(64) not null;