What is the ruling on money earned from working in this field: is it permissible or forbidden, and how can one dispose of it if it is forbidden?

If you leave work without permission or sign the attendance records contrary to the actual time, you are obliged to repent to Allah Almighty by regretting what has passed, abandoning it in the present, and resolving not to return to it in the future. The money you earned for that time must be returned to the employer. If it is impossible to return it, and the work was for a government institution, it must be spent for the benefit of Muslims. If it was for a private institution and it is impossible to return it, then donate it on behalf of its owner, who then has the choice to approve the charity or take their right.