Yes, the other Hawai islands do not have active volcanoes. The eruptions just stop happening… and there is actually a new island forming by volcanic eruption off the coast of the big island!
To become “inactive” it just means the eruptions stop. So erosion and weathering take over. The rocks cool down (become more dense), so there is some elevation loss due to isostatic effect also. Eventually they become dense and eroded to the point they sink below sea level.