I've seen other users delete their own posts so it's definitely something that's enabled. I would expect it to be done via clicking the Edit button on a post. Maybe you can only delete posts in a thread that's yours. Try one in this thread. It's hard to tell for me because I'm not sure which options everyone has and which I have because I'm a moderator. I need to make a test account again. Won't have a chance to do that until tomorrow though.
The profile visitor feature shows you who has looked at that profile. So if I visit your profile (https://guildwarslegacy.com/index.php?user/2078-lady-lyn/) while logged in it'll list me and the timestamp in the visitors section. It's not something you do manually, nor is it something you necessarily need to do anything with. It's just for personal interest, really.
I'm not sure why it's not tracking your activity. Maybe you weren't logged in at the time, or your account is somehow set to not appear on such trackers (invisible status?). Maybe you just need to refresh the page, though that's not the case with me. Try visiting my profile and I'll check if it comes up for me.