Hello! I'd like to ask how to drop observations in such follwing dataset.

See the pic below for dataset.
ID is the identifier of participants, visit is the visit namely visit 1 or visit 2.
Some participants are missing at visit 1 and some are at visit 2, and some values for Blood and urine are missing.

I want to drop all participants if they have missing value both for Blood and urine at visit 1.
I'd like to know if there can be some straightforward and simple method in doing that.
And I can only use the simple code to list the ID by : list ID if Blood==. & urine==.
But since it's a large dataset, it is not practical and also not clever to delete them one after one, like drop if ID==512125 and so on... also with more than 100 variables also not possible for reshaping.

Thanks for help!!!

Array