Ask HN: How should I go about proposing full remote?

I'm at a point in my life where'd I'd like to either take a sabatical, or go full remote. I'm not sure how to word this with my current company though, has anyone gone through this type of experience? How did you approach this topic with your manager?

Last year they allowed one of my coworkers to move away and stay remote, so I'm hoping I can put myself in a similar position.

I'd want to word it as if I'm giving them an ultamatim (Either remote or I quit), but I don't want to come off as demanding or aggressive.