A Microsoft file hosting and synchronization service.
Kai, I have shared with edit access a top level folder with a few people so we can jointly manage the files/folders within and we can jointly manage access to the files/folders within. I am the owner. They and I have created files and folders within and have created links to them which we share with others. That all seems to work.
But, when I go into OneDrive and clean up a lot of old links in the manner described in your answer, the access links to the top level folder I have shared with those few people are also destroyed. My process to clean up old links is, I open "Manage Access" and then check for links. If there are any I delete them. Then I look at People and if there are any direct access links I remove them. Once that is done, there is only one person, me, the owner. There are never any groups. I find that if I use this process, that the people with edit access to the top level folder have lost their access, even though access to the top level folder was never edited. I don't see how to clean up the old links that may have been created without cutting off the access I have given to a few people to the top level folder. This seems to be a pretty elementary process that should work without the need for complex work around.