If you're using Simple route planning, you won't be able to edit routes after they're created and saved. You'll need to delete the planned route and create a new one.
Also, be aware of these other limitations for Simple route planning:
Max 10 addresses per route (excluding starting address);
Max 2 saved routes (regardless of status) per vehicle;
Only the Visit type is available;
The route/addresses cannot be edited after the route is saved;
Any changes besides sequence adjustment are not available;
The name of the route cannot be changed;
The route cannot be reassigned to a different vehicle/driver;
All calculations are done for light vehicles.