A virtual path without a trailing slash mark, if the virtual path is not already the root directory ("/"); otherwise, null.
The VirtualPathUtility.RemoveTrailingSlash(string) method removes a slash mark (/) from the end of the virtual path. If the virtual path is already the root directory ("/"), no action is taken. If the virtual path is null or an empty string (""), the VirtualPathUtility.RemoveTrailingSlash(string) method returns null.