How can one absolve themselves of liability for an amount of 4,0 US dollars that was used from credit cards belonging to other individuals, especially since tracing or contacting them has become impossible?

What you did is theft and treachery, and it is among the greatest sins. You must repent to Allah and return the money to the bank, as the bank is the rightful owner of the money, not the cardholders. This is because the bank bears the damage due to its employees not verifying the identity of the cardholders before transferring the funds. Therefore, send the money to the bank via transfer or check, explaining the reason for sending it, and it is not required to mention your name.