Do you have your data in SAS yet? If not the first step is to read the file. Possibly use the wizard for Import data would be the best start.
Is your membered actually a numeric value or character holding digits? This is import as the techniques would differ.
If the variable is actually numeric then just use:
id = 9999;
If the membered is character with digits then
id = translate(id,'999999999','1234567890');
one way to replace the last n characters
name = cats(substr(name,1,1),repeat('*',length(substr(name,2))));
Personally