UPDATE SET TITLE = TITLE.Split(' ')[0]

UPDATE yourTable
SET TITLE = SUBSTRING(TITLE, 1, CHARINDEX(' ', TITLE) - 1)
WHERE CHARINDEX(' ', TITLE) > 0;

update t set
  t.Title = a.First_Word
from Your_Table
outer apply (
  select top 1
    value as First_Word
  from t.TITLE.STRING_SPLIT(' ')
) as a

create function Get_FirstWord(@words varchar(max))
returns varchar(max) as
begin
  declare @First_word varchar(max);

  select top 1
    @First_word = value
  from @words.string_split(' ');

  return @First_word;
end;

update Your_Table set
  Title = Get_First_Word(Title)