Unsure whom you're apologizing to, but none necessary. Even our little internet refuge here is still a social media site, and social media generally is horrible and frustrating at times. I delete my Twitter app often, only to go back eventually. I think taking a break is healthy at times. I took a several month hiatus from most of the internet after the election, and I'd say it was generally good for my well being. Hubski has the unique feature of changing your username to "user-inactivated" (which I don't care for--we all should have to be responsible for what we put into the world), so it looks like a protest rather than a hiatus. I'd encourage everyone to take a break from time to time, but maybe don't inactivate your account. Just log out. It's that simple and also that hard.
I am glad to hear I am not alone in the cadence of deleting social media apps for a time, only to install them again (and sometimes, repeat). When I really really want to stay off Facebook, I change the password to a random long keyboard smash of numbers and letters. Yes - I can get back in again - but it forces me to go through the password reset process first, which is both annoying and takes a little time; it’s a good barrier to entry.
Facebook is the one that I have the easiest time ignoring. I just find it so banal that I have no interest. I keep my account active purely for the invites and messages. Twitter is my bugaboo. I hate it, because it's such a moronic echo chamber, but I love it because it's such a moronic echo chamber. How many times can I read 500 comments about what a vile rapist Roy Moore is? A lot. Until I can't anymore. Then I can again.
The username should stay. After all, that user said that thing, and therefore the username needs to remain to maintain the attribution. A good comment by a deactivated user is still a good comment. You shouldn't be able to upvote or badge a comment by a deactivated user, but you should still be able to see who made the comment. (My $0.02.)
I think I've deleted Twitter (entire account, not just the app) three times. I technically have an account now, but I only use it to ask questions of businesses. It's been over a year since I wiped my last real account, and I'm never going back. Facebook was purged once, and I never went back. The only one I still use is Instagram. I have one friend who posts text statuses, just screen shots of Facebook, but otherwise the limitation of needing a picture makes it so much more tolerable.