Hello and welcome ,
In which way have you deleted your RSS feed, and which feed are you talking about? From what I can figure out, your blog is
heyjay.coffee and the feed is located over at https://heyjay.coffee/feed.xml.
The subdomain(s) your blog(s) reside on are separate from your username. When you create your first blog at Micro.blog it will be hosted at
yourusername.micro.blog as a default, but it can really be anything as long as that subdomain is available.
Changing your username will not affect the subdomain your blog is at. Unless you explicitly ask @manton to change that as well by sending an email to email@example.com.