what is the line with the numbers above staff called?

hi, what is the line with the numbers above staff called? is there a way to disable it? sometimes I can accidentally remove a bar pressing it
screenshot.2.png

The line is called system track. Alt + T is the default shortcut for showing/hiding it.
see
https://steinberg.help/dorico/v2/en/dorico/topics/write_mode/write_mode_system_track_r.html
https://steinberg.help/dorico/v2/en/dorico/topics/write_mode/write_mode_system_track_hiding_showing_t.html

And you can do cool things with it - for example you can shorten a bar without affecting what comes next.
https://steinberg.help/dorico/v2/en/dorico/topics/write_mode/write_mode_system_track_beats_selecting_t.html
after selecting some beats try clicking the bin icon.

thank you very much!