Hello,
It is not possible to remove existing probe entries. Of course this is easy to understand for probes that were alive at some point, but even "never connected" probes can have references that would break when removing the probe entry. As you noted you can always hide it (from yourself) and if this becomes a real nuisance for others we can look at possibilities to completely remove them.
It's perhaps worth noting that a host can re-key an existing (perhaps never connected) software probe, which can come handy to avoid making unnecessary software probe entries.
Regards,
Robert Kisteleki