CREATE PROCEDURE dbo.SYS_Drop_Column(@TableName nvarchar(200), @ColumnName nvarchar(200))
AS
BEGIN
    DECLARE @ConstraintName nvarchar(200)
    SELECT @ConstraintName = Name FROM SYS.DEFAULT_CONSTRAINTS
    WHERE PARENT_OBJECT_ID = OBJECT_ID(@TableName)
    AND PARENT_COLUMN_ID = (SELECT column_id FROM sys.COLUMNS
                            WHERE NAME = @ColumnName
                            AND object_id = OBJECT_ID(@TableName))

    IF @ConstraintName IS NOT NULL
    EXEC('ALTER TABLE '+ @TableName +' DROP CONSTRAINT ' + @ConstraintName)

    EXEC('ALTER TABLE '+ @TableName +' DROP COLUMN ' + @ColumnName)

END