Deleting posts is technically impossible, you can't delete from the blockchain.
What could be done is removing posts from the steemit.com web frontend by having a blacklist or something like that. That still doesn't prevent people from fishing deleted posts from the block explorer, but they won't be shown on the main site. This is a feature that Steemit could add, not sure if it's in their plans or not.
Your suggestion of a blog site that's under your own control (for domain names, themeing, etc.) is interesting. Pretty much just another version of the steemit.com website that would show only your own posts, correct?
But here is the problem that I see:
If visitors log into your site (to comment or vote on your posts, which would get them rewarded with STEEM), then what is to prevent a malicious site from stealing the user's STEEM credentials? You wouldn't want to give your STEEM account data to an untrusted site.
So users would have to go to steemit.com before they could vote/comment on your posts, which kind of defeats the purpose of having your own site, right?
As far as I understand it, there are ways to live source a website's code. If that's the case then perhaps it would be possible to have people trust the site not to steal credentials? Possibly along with general reputations of different websites this could be possible. Also, if you exclusively use posting keys, the risk would be limited to a malicious site posting something from your account, which I do not particularly see as worth the time and effort to design and maintain a site, but I may be wrong.
Thanks for the informed reply. I figured that was the case on the posts being on the blockchain, and yea a blacklist would suffice. This is the least important item of concern with the topic, however.
Regarding the site. There wouldn't be any login process, or anything along those lines. As for the commenting, it'd just use the standard commenting module with steemit. So, when you're designing your templating, you'd just have a series of variable strings like {{comment_block}} that would be parsed to insert the commenting block at the base of a post.
It wouldn't be another version of steemit.com really. It'd be a subsection of the site that's CNAME'd. So you might have jacobt.steemit.com which would be my blog. Then I can take my domain jacobt.com and setup a CNAME record to point to jacobt.steemit.com.
Then, when you load jacobt.steemit.com it'd have my templating. Now, I'm not necessarily advocating for an all out templating system, although that'd be nice. I'd be content with a simple header/footer wrapper that I could add in my settings. That'd allow for a logo, a simple menu, and maybe some footer details. Then, the blog itself would have your posts in a list fashion, as well as a post view.
Naturally over time, this could be expanded on and new features added, but that'd be enough to satisfy me in the meantime.
Another way to look at this is just a personalized page for your posts. The CNAME is just an extra, so I can have my own nice URL to send people to.