It should be obvious and easy but I don't seem to find how to reset/clear the search/find in sessions in fiddler. The way I usually achieve this is by entering a random string that cannot be found in the captured traffic and this removes the highlighting but I can't believe there is no easier way to do it.
The indeed not obvious way to achieve this seems to be:
Crtl+A ... to select all Sessions
Ctrl+0 ... (Ctrl+Zero) to "Remove all markings of the selected Sessions."
at least that's what I found in "Debugging with Fiddler (Second edition)" page 18