How to delete old voice track carts from RDLibrary

Q: I have a testing Rivendell setup running and I'm unable to delete the old volce track carts, so there's a lot of dirty old carts in here. When I select them at RDlibrary, the delete button is greyed out. What am I missing?

A: Are the logs these voice track belong to still there? Usually they disappear, when the log is deleted. Delete the logs and the carts will disappear with them.