How to add, update and remover resources using resourcemanager in c#?

Question

Hello there I am have successfully loaded the resource manager. But I am not getting suitable ways to add, update or remove resource to the Resource.designer.cs file. For example, here is the code below

ResourceManager rm = ElectronicNapkinCam.Properties.Resources.ResourceManager;
            CultureInfo ci = ElectronicNapkinCam.Properties.Resources.Culture;
            //getting the current value of the resource
            MessageBox.Show(rm.GetString("FilePictureSaveFilter",ci));

Here in the messagebx I can see the value of 'FilePictureSaveFilter', But if I want to update or delete that key as well as value, how to do that? Any code example will be appreciated.