I have an Apple Developer Account, but it's in organization that I no longer work for. How I can leave this organization and buy my own membership in the Apple iOS developer program?
It wasn’t as easy when you asked, but now it’s quite easy to add a new AppleID and then switch roles. Even if the company does not want to do any of the work, you can set up a new AppleID and promote that to the owner and then eject your desired account.
When that is done, you can reapply. I would open a support case with developer support before you start to be sure they can help and you are cleared. They have been exceptionally helpful to us in getting past employees that quit and move the company accounts around as needed. Just give them time to check on things - the more a rush you are in, the more they wonder you’re trying to pull a fast one.