Hi @WhisperyCart948,
This and other settings from the options menu in MSFS are synced to the cloud and will get resynced. You can delete it, but it will come back.
There is a a post in #self-service:wishlist for deleting logbook entries you may want to cast a vote on:
https://forums.flightsimulator.com/t/pilot-logbook-entry-deletion/203103
There are other topics in #self-service:wishlist related to the logbook as well:
Search results for ‘logbook category:163’ - Microsoft Flight Simulator Forums