You can protect a track to prevent accidental changes. While a track is protected, you can’t record on the track, edit regions on the track, or create new regions on the track. If you want to edit the track, you can unprotect it, make the changes, and then protect the track again.
In Logic Pro, click the Protect button 
in the track header.
If the Protect button is not visible, you can show it or configure track header components.
The lock turns green to indicate that the track is protected.
To unprotect the track, click the Protect button 
again.
In Logic Pro, Command-click the Protect button in any track header.
The locks turn green to indicate that all tracks are protected.
To change the state of multiple tracks, click and hold the Protect button of one track, then drag the pointer up or down. The Protect buttons of all swiped tracks switch to the same state.
If the Protect button is not visible, you can show it or configure track header components.
To unprotect all tracks, Command-click the Protect button on any track header.
If you try to make changes to a protected track, a dialog tells you that the track is locked.