It sounds like you saved all your routes and tracks as single overlay file export.
It is better to save each as an individual file permitting you to open just the one you need.
That is probably true, but still is a far from optimal solution.
The problem is, there is no way to see whether (or where) the tracks / routes you have showing in MM on iOS are saved to a file. You can obviously have your own system, but MM gives no clue. If you delee a track / roue (which is the only way to prevent it being displayed) then you've just got to hope you remembered to save it, and that you can find it again. What MM for iOS desperately needs is a way - like the original poster of this thread asked for - is a way to just "hide" a track / route. I really have zero interest in having to manage a set of tracks / routes which are open in MM, and an entirely separate (but overlapping) set of .gpx files containing other tracks / routes. It would be sooooo much easier to use if all of my tracks / routes just lived in MM and *if* i ever want them on a different device i'll export them to a file. If i don't, then i'd like them to just continue to exist in MM, with me able to turn them on and off at will.
There's space in the interface to do it, the same type of buttons already exist to just toggle individual tracks / routes on and off, all it needs is an extra field in MM's datebase somewhere next to each track / route to indicate whether to show or hide that track / route. Then the map display ignores any route not set to display. It's such a basic function, could be implemented to easily, and would make such a huge difference to the usability of routes / tracks.
I note that one of the MM support staff just posted that they'll add someone's request to be able to reverse a route to the devlopment wishlist. If they could add this as well, it's such an easy change it would be massively appreciated.