Note: Not a solution but marked as such to elevate a key reply
Welcome, @anon54407227,
Can you explain the underlying reason why you want to “archive” tasks in the first place?
I ask because I have wide visibility into Asana usage in many organizations over many years, and this need is very uncommon (but perhaps you have some unique requirement?).
For example, if you were to say that your need is that these tasks are cluttering the existing projects, then I’d suggest that, if they’re completed tasks, that you generally have your projects employ the filter to hide incomplete tasks as your default for these projects. Or if not, then consider other approaches for incomplete tasks that will never be done, like:
or perhaps having a collapsed section for such tasks.
Hope that helps,
Larry