NtFreeVirtualMemory

[DllImport("ntdll.dll", ExactSpelling = true)]
[DefaultDllImportSearchPaths(DllImportSearchPath.System32)]
public static extern unsafe NTSTATUS NtFreeVirtualMemory(
    HANDLE ProcessHandle,
    void* BaseAddress,
    uint* RegionSize,
    uint FreeType);

VIRTUAL_FREE_TYPE