I have a panel where each individual is recorded over three round - r3, r4, r5. If for instance, an individual has many variables with missing data in round 4 and 5, and I wish to drop these observations, how do I also drop the round 3 (without missing data) from the same individual.

I've done the following to delete those observations with missing data, but want to remove the observations for the other rounds when one round of an individuals's observations is removed by this command.
. . drop if agemon==.&zhfa==.&ppvt_raw==.&credit==.
(650 observations deleted)