You can delete single axes from an axis group. If automatic labeling is activated, then the other single axes adjust themselves to the labeling order.
To access the command
On the Objects tab 
Grid panel, click
(Delete axes).
Command line: _AstM4CommGridDeleteAxis
To delete an axis from an axis group
- On the Objects tab Grid panel, click
(Delete axes).
- Click the axis to delete and press <Enter>.
- The selected axis is deleted.