$ sbx rm --force m101-clone
Warning: sandbox "m101-clone" runs on an in-container clone (--clone). Any
  commits the agent made inside the sandbox are lost on removal
  unless preserved first. To keep them, before removing run:
      git fetch sandbox-m101-clone
  Fetched branches are mirrored into refs/sandboxes/m101-clone/* and survive
  removal; recover any branch with:
      git branch <local-name> refs/sandboxes/m101-clone/<branch>
  Alternatively, ask the agent to push them to an upstream remote.
Deleting sandbox m101-clone...
Sandbox 'm101-clone' removed
[exit 0]

$ git -C $CAPTURE/fixtures/repo-clone remote -v
[exit 0]

$ git -C $CAPTURE/fixtures/repo-clone for-each-ref refs/sandboxes/
81e11df2aceeb2e92c0b62f2486d8eddc262e55b commit	refs/sandboxes/m101-clone/main
[exit 0]