Hi Joth.
As you are asking how to reset some active paths, I suppose you have run your session in driver mode and you have switched back to surveyor mode while you were in driver mode with some paths already used and active for some trains.
With TRS19+, when you switch back this way to surveyor mode, the current underlying driver simulation is not reset to the initial surveyor mode state but only paused in order to be ready to continue the current driver session when you will switch again to driver mode. This means for tower and paths that all ressources needed for all the active paths are not released but are kept in order to be able to restart the simulation where it was just before toggling back to surveyor.
As editing a path may change the list of the path ressources needed (junctions, signals, crossings, tcbs, exclusive set name, … ), only towers with no path active can be edited. If any path is currently active in a tower Trainz will not authorize to edit the tower or any of its path to prevent breaking some active paths ressource during edition.
To be able to edit a path, you can either use the EIT monitor in driver mode to check for a tower that all its path are inactive before switiching back to surveyor. If all the paths are inactive when you switch back to surveyor, the tower and its paths should be editable. You can even while in driver mode, use the monitor to cancel any path on the fly. But be aware that if you have manually cancelled some active paths, you will probably cannot continue your session when toggling back to driver mode.
Another solution is to quit driver mode and return to the main menu, and then re edit the session in surveyor. This way you will reload your session as it was at the begining of the session with no paths active, and all towers and paths should be editable.
Hope this helps.
Regards.
Pierre.