A piece of code that does what you want is:
declare @sql nvarchar(max), @crlf char(2) = CHAR(13)+CHAR(10);
select @sql = isnull(@sql, '') + 'alter table ' + c.TABLE_SCHEMA + '.' + c.TABLE_NAME + ' alter column ' + c.COLUMN_NAME + ' CHAR(10)' +
+ case when c.IS_NULLABLE = 'YES' then ' NULL;' else ';' end + @crlf
from INFORMATION_SCHEMA.COLUMNS c
where DATA_TYPE = 'date'
-- exec sp_executesql @sql --execute only after inspection!
But I would like to stress that you shouldn't normally do it on a system (except for dev/test purposes), because if it is Date information that you're using, you should be using the proper data type and avoid any other unnecessary cast.