I want to remove that unlock button from the top so a normal users allowed to add a printer from gnome control center. I have added the user to the lp group and it works from the cups web administration page. How can enable any user to access that setting ?
Late reply but I ran into this requirement today and this post is high in the Google results.
In short, you need to apply a local policykit ... policy, that allows the users you want. The file should be created in
/var/lib/polkit-1/localauthority/50-local.d/ named something like
50-printer-open-access.pkla (note, this is the location for policies in debian/ubuntu systems - others I don't know)
Note: please see comments below regarding potential file syntax changes on modern distros, I can confirm the examples below are working on ubuntu 18.04
Example 1, allows literally anyone:
[Printer administration] Identity=* Action=org.opensuse.cupspkhelper.mechanism.* ResultAny=no ResultInactive=no ResultActive=yes
Example 2, allows any users in the
[Printer administration] Identity=unix-group:lpadmin Action=org.opensuse.cupspkhelper.mechanism.* ResultAny=no ResultInactive=no ResultActive=yes
A reference I found handy: