Can not delete workspace from the list


there is a workspace I would not use anymore.
so i want to delete it.
i clicked the name of the workspace,then 404 page returns.
i cannot do anything.
is there anyway to delete workspace from the list?

if i click “clone” and “create workspace”,error message shows up “Workspace with name ‘…/…’ does not exist.”
if i click “open” 404 page returns.