diff --git a/doc/todo.md b/doc/todo.md
index a72a15b..6ffc853 100644
--- a/doc/todo.md
+++ b/doc/todo.md
@@ -31,6 +31,10 @@
 - [x] random access
 - [x] system traits
 - [ ] change filter
+- [ ] resource
+  - [ ] world
+  - [ ] frame
+- [ ] view + iterator
 
 ### maybe support in future
 
diff --git a/include/UECS/Schedule.h b/include/UECS/Schedule.h
index e39800a..36f975e 100644
--- a/include/UECS/Schedule.h
+++ b/include/UECS/Schedule.h
@@ -25,10 +25,6 @@ namespace Ubpa::UECS {
 	// schedule will be clear at the beginning of the next World::Update()
 	class Schedule {
 	public:
-		Schedule() :
-			rsrc{std::make_unique<std::pmr::unsynchronized_pool_resource>()},
-			sysFuncAllocator{ rsrc.get() } {}
-
 		// Func's argument list:
 		// [const] World*
 		// {LastFrame|Latest}<Singleton<Cmpt>>
@@ -115,8 +111,8 @@ namespace Ubpa::UECS {
 
 		std::map<int, std::vector<std::function<void(World*)>>> commandBuffer;
 
-		std::unique_ptr<std::pmr::unsynchronized_pool_resource> rsrc;
-		std::pmr::polymorphic_allocator<SystemFunc> sysFuncAllocator;
+		std::pmr::unsynchronized_pool_resource sysfuncRsrc;
+		std::pmr::polymorphic_allocator<SystemFunc> GetSysFuncAllocator();
 		friend class World;
 	};
 }
diff --git a/include/UECS/SystemTraits.h b/include/UECS/SystemTraits.h
index 1ec1187..d802ddf 100644
--- a/include/UECS/SystemTraits.h
+++ b/include/UECS/SystemTraits.h
@@ -48,6 +48,7 @@ namespace Ubpa::UECS {
 		// register system's name and get an ID
 		// if it is already registered, return it's ID directly
 		Name Register(std::string_view name);
+		void Unregister(NameID);
 
 		// ID must exist
 		void RegisterOnCreate    (NameID, std::function<OnCreate>    );
diff --git a/include/UECS/details/Schedule.inl b/include/UECS/details/Schedule.inl
index 6bff053..35e4346 100644
--- a/include/UECS/details/Schedule.inl
+++ b/include/UECS/details/Schedule.inl
@@ -58,7 +58,7 @@ namespace Ubpa::UECS {
 
 	template<typename... Args>
 	const SystemFunc* Schedule::Request(Args&&... args) {
-		SystemFunc* sysFunc = sysFuncAllocator.allocate(1);
+		SystemFunc* sysFunc = GetSysFuncAllocator().allocate(1);
 		new(sysFunc)SystemFunc(std::forward<Args>(args)...);
 		sysFuncs.emplace(sysFunc->GetValue(), sysFunc);
 		return sysFunc;
diff --git a/src/core/Schedule.cpp b/src/core/Schedule.cpp
index 8ce4936..127497f 100644
--- a/src/core/Schedule.cpp
+++ b/src/core/Schedule.cpp
@@ -6,6 +6,10 @@ using namespace Ubpa;
 using namespace Ubpa::UECS;
 using namespace std;
 
+std::pmr::polymorphic_allocator<SystemFunc> Schedule::GetSysFuncAllocator() {
+	return &sysfuncRsrc;
+}
+
 Schedule& Schedule::Order(string_view x, string_view y) {
 	sysFuncOrder.emplace(SystemFunc::GetValue(x), SystemFunc::GetValue(y));
 	return *this;
@@ -28,9 +32,10 @@ Schedule& Schedule::EraseNone(string_view sys, TypeID type) {
 }
 
 void Schedule::Clear() {
+	auto alloc = GetSysFuncAllocator();
 	for (const auto& [hash, sysFunc] : sysFuncs) {
 		sysFunc->~SystemFunc();
-		sysFuncAllocator.deallocate(sysFunc, 1);
+		alloc.deallocate(sysFunc, 1);
 	}
 	sysFuncs.clear();
 	sysFuncOrder.clear();
diff --git a/src/core/SystemTraits.cpp b/src/core/SystemTraits.cpp
index db4d359..bbc4656 100644
--- a/src/core/SystemTraits.cpp
+++ b/src/core/SystemTraits.cpp
@@ -54,6 +54,19 @@ Name SystemTraits::Register(std::string_view name) {
 	return { newname, id };
 }
 
+void SystemTraits::Unregister(NameID ID) {
+	auto target = names.find(ID);
+	if (target == names.end())
+		return;
+
+	names.erase(target);
+	createMap.erase(ID);
+	activateMap.erase(ID);
+	updateMap.erase(ID);
+	deactivateMap.erase(ID);
+	destroyMap.erase(ID);
+}
+
 bool SystemTraits::IsRegistered(NameID ID) const noexcept {
 	return names.contains(ID);
 }