I'm recalling a short story I read sometime between 1991 and 2010
"Unready to Wear" by Kurt Vonnegut, Jr., originally published in Galaxy Science Fiction, April 1953 which you can read at the Internet Archive. Here is a synopsis from the ISFDB (typos corrected):
A part of humanity has become "amphibious" which means they are able to leave their bodies at will. They have a reserve of very healthy and good looking bodies which can be used at will, most of time they spend as incorporeal happy beings. Those humans who haven't left their bodies consider them deserters.
that involved a guy who had learned to achieve a state of enlightenment in which his mind left his body.
"The mind is the only thing about human beings that's worth anything. Why does it have to be tied to a bag of skin, blood, hair, meat, bones, and tubes? No wonder people can't get anything done, stuck for life with a parasite that has to be stuffed with food and protected from weather and germs all the time. And the fool thing wears out anyway—no matter how much you stuff and protect it!
[. . .]
He went back to reoccupy the body just as the firemen got it breathing again, and he walked it home, more as a favor to the city than anything else. He walked it into his front closet, got out of it again, and left it there."
He could then live "forever" in the ether,
It was true. We hadn't licked death, and weren't sure we wanted to, but we'd certainly lengthened life something amazing, compared to the span you could expect in a body.
and possibly rent a body to experience real life in.
Whenever it's my turn to get into a body and work as an attendant at the local storage center, I realize all over again how much tougher it is for women to get used to being amphibious.
Madge borrows bodies a lot oftener than I do, and that's true of women in general. We have to keep three times as many women's bodies in stock as men's bodies, in order to meet the demand. Every so often, it seems as though a woman just has to have a body, and doll it up in clothes, and look at herself in a mirror. And Madge, God bless her, I don't think she'll be satisfied until she's tried on every body in every storage center on Earth.
He teaches others this skill;
By following the instructions in Konigwasser's book for about two years, almost anybody could get out of his body whenever he wanted to. The first step was to understand what a parasite and dictator the body was most of the time, then to separate what the body wanted or didn't want from what you yourself—your psyche—wanted or didn't want. Then, by concentrating on what you wanted, and ignoring as much as possible what the body wanted besides plain maintenance, you made your psyche demand its right and become self-sufficient.
there is a class of people who vacate their bodies and a class that remain corporeal, finding the idea of losing the connection with their bodies unbearable.
That's why I can't get sore at the enemy, the people who are against the amphibians. They never get out of their bodies and won't try to learn. They don't want anybody else to do it, either, and they'd like to make the amphibians get back into bodies and stay in them.