To make Piwik a bit more awesome it would be good to have an "Undo" feature wherever possible. Ideally this would be implemented with a "Manage Entity Component" in #6951 and this way work out of the box for all components. More and more other apps offer such a feature and it is very useful. It is surely not always easy to build and we cannot add it to all "Manage Entity" screens now just like that.
The issue itself could be maybe just good to keep it in mind when working on #6951 and for when developing new features.
For some features it would be rather easy to add, such as in "Manage Custom Alerts" and "Manage Scheduled Reports", for some it is much harder to do eg for "Delete Website" (as we delete a lot of related data via an event in several other tables when a website is deleted).