Severe ankle sprain in soft cast during the day or bandage for home, i take it off to sleep. how long before i can let the crutches go and walk on it?

Depends: Without a proper exam, it's hard to say. Sprain treatment can range from a few weeks of compression to months of casting or even surgery. The best person to ask is the doctor treating you, whether it be an orthopedist or podiatrist. If you don't allow adequate healing time, you risk an unstable ankle.

Ankle sprain: With a severe ankle sprain you will want to use crutches for 2-3 weeks.Once you can walk without pain you can discard one crutch and then after few days to a week later you can discard the other crutch.

Healing times vary: Healing times may vary depending on the individual and on the severity of the injury. Pain and swelling may last a long time. The pain and swelling will usually improve over the course of the first few weeks. When you are able to put pressure on it without any significant pain and instability you may be able to wean yourself off of the crutches. Consult with your doctor.