I have to extract all the delete performed within a certain range time period but only the ones without where condition .
Seems like a strange requirement to me. Especially since no matter how you do that it won't necessarily find ALL of the DELETE statements that do what you are trying to find. That is because there are a lot of ways to write a DELETE statement with a WHERE clause that will do the same thing as a DELETE without a WHERE clause: e.g. WHERE 3 > 2 will always be true so is the same as not even using a WHERE clause.
select * from
v$sql where sqltext like 'DELETE%'
"but" not like 'DELETE% WHERE%';
If you simply must do it just use a LIKE that includes a DELETE combined with a 'AND NOT LIKE ...' that includes the WHERE.
I has already made
WHERE SQLTEXT like 'DELETE%'
AND SQLTEXT NOT LIKE 'DELETE% WHERE%'
It extracted both the DELETE statements, with or without WHERE CONDITION.
Regular expression using regexp_like:
something like this (i haven't tested, you have to experiment) :
where regexp_like(sqltext,'^DELETE [^WHERE]')