Access rules for edit, delete notes?

[listy]

I guess it is not possible from the ui.
But nothing can stop You from edit source codes of discussion widget.
Looks like You on the 4.5 or lower version.

src/pyasm/widget/discussion_wdg.py

Method: get_note_menu
You should add some custom security rules, and add security checks
Example:
#<rule group="project" code="*" access="allow"/>
security = Environment.get_security()
key = { "code": "*" }
if security.check_access("project", key, "allow", default="deny"):
etc...