How to remove constraints from my MySQL table?

If the constraint is not a foreign key, eg. one added using 'UNIQUE CONSTRAINT (colA, colB)' then it is an index that can be dropped using ALTER TABLE ... DROP INDEX ...

I had the same problem and I got to solve with this code:

ALTER TABLE `table_name` DROP FOREIGN KEY `id_name_fk`;
ALTER TABLE `table_name` DROP INDEX  `id_name_fk`;

Mysql has a special syntax for dropping foreign key constraints:

ALTER TABLE tbl_magazine_issue
  DROP FOREIGN KEY FK_tbl_magazine_issue_mst_users

There is no such thing as DROP CONSTRAINT in MySQL. In your case you could use DROP FOREIGN KEY instead.