I created a logger with a typo and went to delete it but found that I could not get the "Delete Logger" button to enable.
I tried clicking away from the logger and back and I tried clicking away from the section and back. I also tried right click.
I was able to delete by resetting all to default levels but that also wipes out any other changes you may have made (both loggers added and special configurations).
This appears to be an NX3 specific issue; I did not have this issue in NX2.
I only tested the SNAPSHOT (Cowbell) at this time, not older versions of NX3.