Currently member of site can share a document in a document library unless this feature has been disabled. Sharing a document is a good feature and allows the sharing for both internal and external users. It is much easier than complex permission management. However, people make mistakes.

Currently site member is able to stop sharing. If the member shares a document by accident, she/he is not able to undo the mistake. Only site owners have Stop sharing available for them. And even then the stop sharing works in a bit weird fashion - it removes the permission from everybody except from the other owners. Even the member who created and shared the document has no longer access to it.

Please, allow members to stop sharing for the documents they have shared.