Tables too large

I’ve noticed that the wp_watupro_student_answers and wp_watupro_taken_exams tables are taking up a lot of space on the server hosting my website. Much more than all the other tables in my WordPress installation combined.

Is it safe to empty these tables?

Sure I would back them up beforehand, even just to keep a record of the quizzes already taken, but I’d like to know if clearing them will affect the plugin’s functionality.

Thank you in advance!