Unpublishing and republishing

You can: but I wouldn't pull the book completely. Rewrite it and then upload the newer version. That way you won't lose any reviews you already have--at least, I don't think you will. I'm sure someone else will come along to advise who is sure about this.

Meanwhile, don't beat yourself up about it. And consider writing something new instead of trying to change the past. You're good.

You can but you will need a new ISBN

Yes. You can unpublish any book you want and reload with another file later and still keep any reviews and rank, etc. when it republishes. (I've done this. Once because I doubted a book and pulled it for a while and also to move Pronoun-distributed titles back to Amazon.) No need for a new ISBN if that's all you're doing. If you want it to be treated like a completely new release, then that's different and you'd need to publish as a new book with a new ISBN, etc. But I know more than one author who has cleaned up a previously-published book without publishing it as new.

On your Kindle bookshelf you have the choice to unpublish or delete. It's explained here in the help section on KDP:

Just be sure not to do it more than once, it is an old trick to reappear on the new releases list--but one that Amazon disapproves of.