When it is safe to remove RigidBodies and constraints?

Hi, all!
Recently I got random crash with Bullet. The debug shows it happens after removing of RigidBodies + Constraints
(after ragdoll recovery)

#0  0x00005555563f63aa in btCompoundCollisionAlgorithm::preallocateChildAlgorithms(btCollisionObjectWrapper const*, btCollisionObjectWrapper const*) ()
#1  0x00005555563f6a25 in btCompoundCollisionAlgorithm::processCollision(btCollisionObjectWrapper const*, btCollisionObjectWrapper const*, btDispatcherInfo const&, btManifoldResult*) ()
#2  0x0000555555d903e4 in btCollisionDispatcher::defaultNearCallback(btBroadphasePair&, btCollisionDispatcher&, btDispatcherInfo const&) ()
#3  0x0000555555d90698 in btCollisionPairCallback::processOverlap(btBroadphasePair&) ()
#4  0x0000555556400cc2 in btHashedOverlappingPairCache::processAllOverlappingPairs(btOverlapCallback*, btDispatcher*) ()
#5  0x0000555555d8fa7c in btCollisionDispatcher::dispatchAllCollisionPairs(btOverlappingPairCache*, btDispatcherInfo const&, btDispatcher*) ()
#6  0x0000555555d4416c in btDiscreteDynamicsWorld::internalSingleStepSimulation(float) ()
#7  0x0000555555d3e3ba in btDiscreteDynamicsWorld::stepSimulation(float, int, float) ()
#8  0x0000555555cd5d62 in Urho3D::PhysicsWorld::Update(float) ()
#9  0x0000555555cdbbc1 in Urho3D::EventHandlerImpl<Urho3D::PhysicsWorld>::Invoke(Urho3D::HashMap<Urho3D::StringHash, Urho3D::Variant>&) ()
#10 0x0000555555be52fb in Urho3D::Object::SendEvent(Urho3D::StringHash, Urho3D::HashMap<Urho3D::StringHash, Urho3D::Variant>&) ()
#11 0x00005555560cd987 in Urho3D::Scene::Update(float) ()
#12 0x00005555560d0551 in Urho3D::EventHandlerImpl<Urho3D::Scene>::Invoke(Urho3D::HashMap<Urho3D::StringHash, Urho3D::Variant>&) ()
#13 0x0000555555be5ad7 in Urho3D::Object::SendEvent(Urho3D::StringHash, Urho3D::HashMap<Urho3D::StringHash, Urho3D::Variant>&) ()
#14 0x0000555555c0c58d in Urho3D::Engine::Update() ()
#15 0x0000555555c0da93 in Urho3D::Engine::RunFrame() ()
#16 0x0000555555c0aaf5 in Urho3D::Application::Run() ()
#17 0x000055555587ba3a in RunApplication () at /home/slapin/dungeon/rework/Urho3DPlayer.cpp:48
#18 0x000055555587bae1 in main (argc=1, argv=0x7fffffffe248) at /home/slapin/dungeon/rework/Urho3DPlayer.cpp:48

Looks like Bullet detected collision of nonexistent RigidBody. So I wonder how to safely remove RigidBodies and constraints. (Disabling these lead to the same result).