I had deleted routes reappear yesterday while using Trip Manager that
@FrankB was kind enough to share with all of us. (It is a great tool.) I'm not using the Tread app at all - no syncing to Explore database.
I had created a route in a gpx file, then used Trip Manager's "Send to device" to send [only] a trip file to my XT2, [via USB cable connected to my pc). I restarted the zumo and opened the route, which recalculated it. All was well.
The zumo did appear to create a current.gpx from the trip when it calculated the route - that makes sense to me.
I decided to change my route, which I did on the pc. I used Trip Manager to delete the first trip file, then, as before, send the new gpx as a trip to the zumo. After restarting the zumo, I now had both the new and old (deleted) routes on the zumo. I reconnected Trip Manager and saw I now had two trip files, the one I had just sent, and one that had been recreated. The recreated one held the previous version of the route and had the normal cryptic zumo file name.
Thinking I might be losing mind, I carefully deleted both trip files, using Trip Manager. Then I made yet another route change on the pc and, as before, used Trip Manager to send the 3rd version of the gpx route to the zumo as a trip. I restarted the zumo and now had all 3 versions of the route, and 3 trip files.
Wondering if the zumo was somehow syncing to the Explore database through my pc, I checked my Explore account. The route were not there. I expected that to be the case, but wanted to be sure.
I then deleted all 3 routes, using the zumo itself, then checked with file explorer on the pc to verify that all 3 trip files were gone.
I then restarted the zumo and found the that 2nd version of the route was back again!
I poked around the zumo's file system, but could not figure out where the route(s) are being restored from.
I deleted the route once again, using the the zumo again, and it has stayed gone - at least so far!
So, apparently, when deleting routes, as the saying goes, "if at first you don't succeed, try, try again."
Things could be worse. Restoring unwanted routes is a lot better than losing wanted routes.