I have installed a new theme in Cinnamon desktop environment, but suddenly it became read-only. Where is these themes located at, for me to delete them manually?
Remove Cinnamon read-only theme
cinnamon;theme;readonly
System themes are located in /usr/share/themes. Run sudo nemo to start a rooted file manager session, then delete the theme you want, or from a terminal sudo rm -rf /usr/share/<theme-name>.Note that every file in /usr/share should have the read and write bits set for all users/groups, and if this isn't the case you can file a bug to the effect that a theme was erroneously installed with incorrect permissions.