How can I remove an invalid namespace from the dashboard?

[tuzkiiiii233]

When importing translation files, I forgot to assign an existing namespace, which resulted in a large number of entries being imported with the namespace set to <none>. These entries are now effectively invalid.

I’d like to batch delete this data. Is there a simple and efficient way to do this?
Also, how can I remove or clean up these invalid <none> namespaces?

Note: There are over 1,000 translation entries under the <none> namespace.