Is it obligatory to immediately quit haram work and get rid of the money earned from it, given the unavailability of other job offers and the possibility of parental objection?

Working in mixed companies—those with both permissible and impermissible elements—is not absolutely forbidden. Rather, it is forbidden to work in the impermissible fields within them. Therefore, there is no objection to you working in the aforementioned company as long as you avoid writing or recording usurious contracts, as doing so would be an affirmation of them. The salary here depends on whether the work is permissible or impermissible. If the work is permissible, the earning is permissible; if it is impermissible, the earning is impermissible. If it is mixed, the impermissibility in the salary is proportional to the impermissible work. Thus, there is no objection to you remaining in your current job while avoiding the recording of usurious contracts until you find a purely permissible job.