It depends on who you want to hide it from. For a person who has little experience, who has studied several CMS platforms vs pure code, it won't matter which plugin you use anymore. There are tools and methods that can show you which platform you use, which technology, when you made the first and last change to the website and so on. This is what you use against those who scan for websites.

Write in pure code, but your client must also understand that there are huge costs. It's like when you want to have the best car the way you want it, you do NOT build your own car factory, you choose a car, a model that you can afford, and that satisfies the most or most important requirements.