A family member was living with me and left after running up some bills. Can I put their stuff in the apartment building hall and change the lock because this person will wait until I am gone steal my stuff while they are taking out theirs?

Do you have any proof they abandoned the apartment? If you lock them out and put out their belongings without warning or court order, you could be sued.

We need more of the details (how long they were there, circumstances of leaving, how long gone) to be able to advise further.

We could use more details but no and no. You can not change the locks and can not put the belongings outside.

If they have already moved out, * they are not staying there, you may change your locks, but you have to provide them a date and time to pick up their things. You may ask a police officer to be there to pick up their belongings.

The "iffy" is are they moved out or not, if they are not really moved, then you can not change the locks either