If you want fix this immediately, you have to amend this by hand by using the database explorer. Nevertheless Airnav is working on mechanisms to gain correct routing information from all users with boxes close to airports, who have their boxes running with data-sharing switched on. These new routines have already delivered an improvement to the correctness of route information (From & To & VIA), but it's still a quite long way until they are close to be perfect.
Additionally there are several other reasons for false route informations, like diversions, change of routings of the used flight id, human error, weak or no radarbox coverage on one or both ends of a flight, old or outdated data in your Navdatabase, old and/or outdated data in database on Airnav Servers and finally the not uncommon glitches in Software...