Leaving has a negative connotation

Does it? What alternative accurate wording would you suggest? Everything else I can think of is euphemism. Leaving a job is ... leaving a job. It doesn't say why.

Handing-off (to XYZ), stepping down from his role, retiring as CEO, etc.

I would say none of those are euphemisms, they just put the emphasis on the reason why as opposed to the act of leaving itself

When you leave, one has to be "left behind". It doesn't speak to an amicable outcome.

Do you only leave the grocery store after a fight?

I think you’re reading much more into this.

You don't see a difference between leaving a leadership position and leaving a grocery store?

Well, either they are, or the PR department is reading too much into it and s/he's just explaining the reason why PR departments avoid it.

I think you're being naive to the way corporate communications work.

Go home and spend time with your family.