I am running Nightly and have an add-on “HP Smart Web Printing” which has been disabled as it is not signed.
I am getting the message “HP Smart Web Printing could not be verified for use with Nightly has been disabled”.
Disabled add-ons appear to have all “buttons” hidden/removed.
How do I (or anybody else) removed disabled add-ons from Firefox (Nightly)?
How was the add-on installed? Add-ons installed in the profile directory should be removable, but add-ons installed globally won’t be removed until you remove the software that installed them.