How to release a DLL that was loaded with Reflection? [duplicate]

This question already has an answer here:

• Hot Unload/Reload of a DLL used by an Application 3 answers

String dlls = ConfigurationManager.AppSettings["ApiFolder"];
FileInfo[] files = new DirectoryInfo(dlls).GetFiles("*.dll");
foreach (FileInfo file in files) {
    if (!LoadedApis.ContainsKey(file.Name)) {
        Assembly ass = Assembly.LoadFrom(dlls + file.Name);
        foreach (Type t in ass.GetTypes()) {
            if (t.GetTypeInfo().FindInterfaces((x, y) => true, null).Contains(typeof(IApi))) {
                IApi api = (IApi)ass.CreateInstance(t.FullName);
                LoadedApis.Add(file.Name, api);
            }
        }
    }
}

I'm using the above code to load all DLLs that have a particular interface from a folder into a dictionary where I can access them later. I'm working on a plug in system where all you have to do is drop in a DLL and it will be loaded and used.

It's working great but there's one use case I want to account for that I currently don't know how to do. I want to allow for the DLLs to be removed or updated.

Is it possible to release a DLL that has been loaded with reflection so that it can be deleted or overwritten? I imagine I'll have to make a few interop calls but I don't know which ones to make.

Or, a different approach, can I load the DLL into memory so I never have a lock on the file to begin with?