I had the situation that I imported some certifiates to my database in STRUST (trust manager).
I found these instructions but unfortunatelly when I try this, I can't because the delete button is grey (deactivated)

The solution was to allow repository & cross client modification (SCC4) for the client I managed the certificates in.
So in my case this was client 000.
This document was generated from the following discussion: Delete Certificate from STRUST Database