Altering the data type of a column 

Changing the data type of a column after it is defined or added to a table using ALTER TABLE.

Using ALTER TABLE, you can change the data type of a column after it is defined or added to a table.

Procedure

Change the favorite_color column to store as text instead of varchar by changing the data type of the column.
ALTER TABLE cycling.cyclist_alt_stats ADD favorite_color varchar; 
ALTER TABLE cycling.cyclist_alt_stats ALTER favorite_color TYPE text;
Only newly inserted values will be created with the new type. However, the data type before must be compatible with the new data type specified.