printtool keeps requesting admin to modify admin settings
from https://discussions.apple.com/thread/7269124:
Terminal
sudo dseditgroup -o edit -n /Local/Default -a USERNAME -t user _lpadmin
GUI

Open spotlight (cmd-space) and search for Directory Utility
Click the lock to make changes, then select Directory Editor, then select Groups from the Viewing popup menu.
Type print in the search field to quickly access Print Administrators. Select Print Administrators, then GroupMembership.
Click the very subtle “+” at the right side of the GroupMembership line, then type the name of the user overwriting “new_value” which is already selected, just waiting on you to type.
Save and quit Directory Utility. I’m not sure if it takes effect immediately or if you need to log the user out and back in.