Unused SLP definition version cleanup delay - Not Cleaning Versions

HI there,

I modified this value under master server properties / SLP Properties:

Unused SLP definition version cleanup delay 10 seconds.

However, my SLP's still have many old versions associated. I can see the versions using the nbstl command.

How can I force a cleanup of all versions? Basically, I'm trying to delete an STU and get an error that it is still referenced in an SLP (version 4)

Thanks!