How to edit or delete midi notes in midi track layers?

What I do in such cases, where I might need to revert back before edits is easy.
Simply first, before you edit anything, right click on the track and select (Duplicat Track (Complete). Mute, the 1st track, ir turn off the sound for those events to edit. Use the 2nd duplicated track to create your edits. You always have the initial track to revert back to.
If you dont wish to create a track, you can duplicate the event(s) on the same track, and slide them past the end of the song as a reference.