Store, retrieve and delete settings in C# Registry
Quick remarks:

When you're copy-pasting code, you should realize you're doing the wrong thing. The first four lines of each of your methods are exactly the same, and thus should become a method that returns a RegistryKey.

Do not needlessly abbreviate. softKey, compKey, appKey and secKey are all unclear.

Do not use Hungarian notation. Even if the type isn't clear from a parameter's name, your IDE will tell you what type it is.

Why doesn't DeleteSetting use GetSetting to retrieve the value?