I've seen some mobile apps keep the password change section separate from the profile edit screen (e.g. Instagram), but others only on the profile edit screen.
I personally am used to looking for the settings icon whenever I want to change my password. However, since my app isn't really that big and doesn't have much to do, I should just remove the settings and change the password in the editing profile.
My app currently has this type of structure:
My profile has the option to edit the profile.