One word substitution

Anonymouswhen a student is unattending the college but goes to write examinations in the college.

I don't know what you mean by "unattending" the college. Can you say this another way?

I assume that you are referring to distance learning or distance education, which is where students don't physically attend the college but communicate with their instructors via some form of network. I don't think there's a special term to differentiate between those courses that have mandatory gatherings—such as exams held at the college—and those that don't.