Completely getting rid of an app

I've been finding mixed info regarding this topic.

Here is what I want to do. I initially installed numerous apps, like around 60 or so on my iMac from the App Store (hundreds on my iPad/iPhone).

Of course, the app store has no way you can try out programs, so I had to buy them to see if I liked them. Out of these 60 apps, now there's only like a dozen that I find usefull and use daily.

Here is all I want to do -- I'd like to get rid of the rest.

I mean completely. I don't want to see them in my app store, I don't want them on my computer -- I want them completely gone from my sight, so that next time I do a clean install, or buy another Mac -- I can simply go to the app store and quickly download those essential programs without having to remember which ones they are, or scrolling down pages and pages of useless data.

I can easily get rid of apps on my iMac -- darn if I can find a way to remove them from my record history or the apps store, so they are not listed under my "purchases".

Eventually, I'd like to do this for my iPhone and iPad as well, but darn, I have hundreds of apps I don't use anymore, and that's going to take forever.

Please tell me, that Apple, as it doesn't give you a chance to try software -- has a way to do simple house cleaning of apps through all their devices so they can be removed, if you don't want or use them anymore.

Any help, appreciated.

Moe