To edit the boot loader configurations in openSUSE,
From menu, click Computer – YaST
Click System – Boot Loader. This launches the Boot Loader settings editor.
Once in, to delete an entry, select the entry and click Delete.
To move up or down in the order, select the entry and click Up or Down as required
To edit an entry for instance to change the display Name or set password protection, select the entry and click Edit.
Set or Change Default
To set an entry as default, select the entry and click “Set as Default”
Advance Edits & Options
To edit the config files for the selected boot loader (default is GRUB), click other button and select the options like “edit configuration files” or start from scratch”
For advanced options like changing the default GRUB boot loader to say LILO, click the “Boot Loader Installation” tab.
Once done, click Finish to apply the changes to the system.