All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The repentance of this person would be by stopping doing this injustice and regretting for having done it and being determined not to do it again while giving back the rights to its owners. If he has no money to repay the rights then it is a debt which he is obliged to repay when he becomes able to do so unless he seeks the forgiveness of the people who have rights on him and they forgive him. For more benefit, please refer to Fatwa 86374.
In case they don’t agree to forgive him and he is unable to give their rights back to them, then he should perform good deeds as much as possible especially seeking Allaah’s forgiveness and supplicating Him. It might be that Allaah will repay these rights on his behalf.
Allaah Knows best.