Delete rows where matched value is twice as much
If you want to DELETE all the information in table1.*:

DELETE table1.*
FROM test.table1
JOIN test.table2 ON (table2.id = table1.id)
WHERE table1.price &lt; (table2.price*2);


This will DELETE all rows from table1 that match with the WHERE criteria. If you want to DELETE all the rows that match against the WHERE criteria in table2, just replace DELETE table1.* to DELETE table2.*.

As the MySQL's documentation says: 

Multi-Table Deletes 


  You can specify multiple tables in a DELETE
  statement to delete rows from one or more tables depending on the
  condition in the WHERE clause. You cannot use ORDER BY or LIMIT in a
  multiple-table DELETE. The table_references clause lists the tables
  involved in the join, as described in Section 13.2.9.2, “JOIN Syntax”.
  
  For the first multiple-table syntax, only matching rows from the
  tables listed before the FROM clause are deleted. For the second
  multiple-table syntax, only matching rows from the tables listed in
  the FROM clause (before the USING clause) are deleted. The effect is
  that you can delete rows from many tables at the same time and have
  additional tables that are used only for searching:


 DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.id=t2.id
 AND t2.id=t3.id; 



  Or:


 DELETE FROM t1, t2 USING t1 INNER JOIN t2 INNER JOIN t3 WHERE
 t1.id=t2.id AND t2.id=t3.id;



  If you use a multiple-table DELETE statement involving InnoDB tables
  for which there are foreign key constraints, the MySQL optimizer might
  process tables in an order that differs from that of their
  parent/child relationship. In this case, the statement fails and rolls
  back. Instead, you should delete from a single table and rely on the
  ON DELETE capabilities that InnoDB provides to cause the other tables
  to be modified accordingly.
  
  Note If you declare an alias for a table, you must use the alias when
  referring to the table:


 DELETE t1 FROM test AS t1, test2 WHERE ...



  Table aliases in a multiple-table DELETE should be declared only in
  the table_references part of the statement. Elsewhere, alias
  references are permitted but not alias declarations.