What to do if mysql show foreign keys?

If mysql show foreign keys - Firstly, find out your FOREIGN KEY constraint name in this way:

SELECT
  TABLE_NAME,
  COLUMN_NAME,
  CONSTRAINT_NAME,   -- <<-- the one you want! 
  REFERENCED_TABLE_NAME,
  REFERENCED_COLUMN_NAME
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
  REFERENCED_TABLE_NAME = 'My_Table';
You can also add (to the WHERE clause) if you have more than one table called My_Table in different schemas.
AND TABLE_SCHEMA = 'My_Database';
And then you can remove the named constraint in the following way:
ALTER TABLE My_Table DROP FOREIGN KEY My_Table_Constraint;