What is the way to deliver or transfer the amount for freeing a slave after the death of Sheikh Abdul Aziz?

There is no known way to free slaves in this era. It is out of Allah's mercy to His servants that He has provided them with alternatives to freeing a slave for expiations, either fasting or feeding. Therefore, one should look at the type of expiation required for them and resort to its alternative as long as they are unable to free a slave. If they are unable to perform the alternative, then it is waived for them.