If it is numeric and you are happy to lose the values of the other variables where your variable is missing then you could try the following:
data have;
infile datalines dsd;
input
seq_id : $8.
my_var : 8.
;
datalines;
1,12341234
2,.
3,.
4,.
5,12341234123
6,.
7,.
8,.
9,123412341234
10,.
11,.
12,.
13,12314123124
;
data want;
set have;
where not missing(my_var);
run;
If you need something else then please please provide what output you require.
Thanks & kind regards,
Amir.