Archival And Removal
All entities can be archived and removed.
Being archived is simply a state of that entity that it can enter, but cannot exit. The entity cannot change in any way after archival.
The use of archival is to get rid of old entities from the set of things you are actively looking at or that you need. For some entities this is a natural end state (inbox tasks, big plans, etc.), for others it is rather an exception (docs, smart lists, etc.).
Archival can be triggered by a command - either from the WebUi (the trashcan on certain entities) or from the CLI app. It can also be triggered on certain entities automatically. Completed tasks and big plans, or old memory.txt files are treated like this.
Entities that are linked are generally archived together. So if you're archiving an inbox task, it's linked notes, time events, etc. are also archived.
Entities that are archived still exist in the system and can be accessed.
A removal however destroys the entity permanently. It will not exist in the system anymore, and cannot be undone.
Entities that are linked are generally removed together.
You need to first archive, and then you can remove entities.