You can't permanently delete any item from your purchase, but you should be able to hide them via your computer's iTunes, that should stop them showing in the cloud for redownloading.
On the current version of iTunes click on your name towards the top-right of the iTunes screen, and then click Purchased on the popup

Or click on the Purchased link under Quick Links on the right-hand side of the iTunes store homepage.
Select the Apps section of Purchased, and click on the top left corner of an app that you want to hide (you should get an 'x' show on that corner, but on the current version of iTunes its invisible, it doesn't show on my Mac's iTunes and other people have posted the same comment, but clicking on the top left corner should still hide the app).
Hiding and unhiding : iTunes Store: Hiding and unhiding purchases - Apple Support