I think I have to disagree.
The free books are a great way to meet new authors. Some are not good reads, but it is easy enough to delete a book. Easiest way, for me, is to connect to my computer and delete the book(s) from the Documents File.
Perhaps you misunderstand . . . I agree the 'free' offerings are a great way to find new authors. But I'm talking about getting every free thing that comes along without discriminating. In my case, I picked up a bunch of stuff like romances and chick lit which I have NEVER been interested in -- even as an angsty teen.

Now I look back and wonder why I 'bought' them? I won't ever EVER read them. . .so I'm deleting.

OTOH, I do like mysteries, adventure, some sci-fi, thrillers, etc. . . .and have definitely 'bought' some of them for free even by authors I'd never heard of before. . .and some of those have become new favorites. I probably would have even 'bought' them for actual money, but I only found out about them because they were offered free.
I will also say that I really don't get books from anywhere than Amazon. The few times I did I either found the book to be absolutely 'not ready for prime time' or there were really wonky formatting errors or corruption issues. So got burned there and won't do that again.
As to deleting. . .it is perfectly easy to delete a book from the Kindle. . .just left click and click delete . . .but to make it GONE from your Amazon archives you have to go through Manage Your Kindle on the Amazon website. As I have nearly 1300 books (before yesterday I would have said over 1300

) it's a bit of a chore.
And FWIW, I would NOT recommend deleting it by connecting it to the computer and deleting it as you would any old file. I don't think that necessarily removes all its bits -- if you've made any notes or marks those are stored in a different, associated file, for example. And if it's a book you want off the Kindle but not gone completely, well, you've used up one of the licenses by doing it that way. At some point you
may run up against the simultaneous device usage limit. And it's NOT gone permanently from your archives.