DropRasterConstraints — Drops PostGIS raster constraints that refer to a raster table column. Useful if you need to reload data or update your raster column data.
boolean DropRasterConstraints(name 
            rasttable, name 
            rastcolumn, boolean 
            srid, boolean 
            scale_x, boolean 
            scale_y, boolean 
            blocksize_x, boolean 
            blocksize_y, boolean 
            same_alignment, boolean 
            regular_blocking, boolean 
            num_bands=true, boolean 
            pixel_types=true, boolean 
            nodata_values=true, boolean 
                out_db=true
            , boolean 
            extent=true);
boolean DropRasterConstraints(name 
            rastschema, name 
            rasttable, name 
            rastcolumn, boolean 
            srid=true, boolean 
            scale_x=true, boolean 
            scale_y=true, boolean 
            blocksize_x=true, boolean 
            blocksize_y=true, boolean 
            same_alignment=true, boolean 
            regular_blocking=false, boolean 
            num_bands=true, boolean 
            pixel_types=true, boolean 
            nodata_values=true, boolean 
                out_db=true
            , boolean 
            extent=true);
boolean DropRasterConstraints(name 
            rastschema, name 
            rasttable, name 
            rastcolumn, text[] 
            constraints);
Drops PostGIS raster constraints that refer to a raster table column that were added by AddRasterConstraints. Useful if you need to load more data or update your raster column data. You do not need to do this if you want to get rid of a raster table or a raster column.
To drop a raster table use the standard
DROP TABLE mytable
To drop just a raster column and leave the rest of the table, use standard SQL
ALTER TABLE mytable DROP COLUMN rast
the table will disappear from the raster_columns catalog if the column or table is dropped.  However if only the constraints are dropped, the
        raster column will still be listed in the raster_columns catalog, but there will be no other information about it aside from the column name and table.
Availability: 2.0.0
SELECT DropRasterConstraints ('myrasters','rast');
----RESULT output ---
t
-- verify change in raster_columns --
SELECT srid, scale_x, scale_y, blocksize_x, blocksize_y, num_bands, pixel_types, nodata_values
    FROM raster_columns
    WHERE r_table_name = 'myrasters';
 srid | scale_x | scale_y | blocksize_x | blocksize_y | num_bands | pixel_types| nodata_values
------+---------+---------+-------------+-------------+-----------+-------------+---------------
    0 |         |         |             |             |           |             |