data want;
set have;
if time_interval<='00:00:00't or time_interval>'01:00:00't then delete;
run;
As a side issue, the variables are not "formatted as time variables", they are time variables, representing the number of seconds after midnight, or if you really have an interval, the value is the number of seconds in the interval. The format used is irrelevant to the above code, which will work however the variable TIME_INTERVAL is formatted and will work if the variable is not formatted.
--
Paige Miller