Welcome to the Streamlit community, and thanks for your question! 
What you’re seeing is likely due to how Streamlit Community Cloud organizes “workspaces.” If you’ve ever had a shared GitHub repo or app with someone, their workspace may appear in your dropdown—even if the connection was years ago. This doesn’t mean you have admin access to their apps, just that you can see the workspace and any public apps within it. There isn’t currently a user-facing option to manually remove or unlink these workspaces from your dropdown.
If you want to fully disassociate, you’ll need to ensure you’re no longer a collaborator on any shared GitHub repos or organizations with that user. If the workspace still appears after that, it’s a known limitation, and you may need to contact Streamlit support for further help. For more details, see the discussion in the Streamlit forum and the official docs on workspaces.
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