If you want Opus not to use the Recycle Bin by default then you just need to flip the checkbox under Settings -> Preferences -> File Operations -> Deleting Files.
If you want Opus to use the Recycle Bin normally, but have a special button for deleting without using it, then the command is:
Delete NORECYCLE FROMFOCUS
Note that the default toolbar's Delete button runs this command:
Delete SHIFT FROMFOCUS
The SHIFT argument means that if Opus is configured to use the recycle bin and you hold shift when clicking the button, the delete will not use the recycle bin.
(If the recycle bin is switched off in preferences then the meaning of the SHIFT argument changes. See the Opus Raw Commands section of the manual for full details.)
Edit: Corrected above.
For a tutorial on button editing, watch this video:
[Toolbar Editing (video tutorial))
As for user commands, they are very rarely needed or used. They let you define a command in one place and then use it in several places, but it isn't often that people need to do that. You can probably ignore them for now. Just create / edit buttons directly on your toolbars instead.
If you meant that you wanted examples of user-editable commands then lots of them come with Opus. Every single toolbar button and menu item is user-editable.