Did you delete those ghost routes in the app while they were still toggled ON for the watch and THEN sync?
If so, this has worked for me on other watches (A3P, SSU):
Toggle the maximum number of your App’s routes (15) onto the watch and sync.
Check to see that those ghosts have been overwritten.
Toggle all the routes back OFF the watch and sync again.
Check to see that the ghosts are gone.
With the A3P this sometimes took a few attempts.