If the Marker track is hidden, you can rename markers directly in the ruler.
In Logic Pro, Command-double-click a marker, then enter a new marker name.
In Logic Pro, select the marker in the Marker List.
Do one of the following:
Click the Marker Text Edit button.
Double-click in the Marker Text area.
Enter the new marker name in the Marker Text area.
The first portion of text in the window is used as the marker name.