This tweak restricts Finder to a simple interface that restricts access to files not on the Desktop, and applications not in the Dock.
Start a new Terminal session (in Finder click Applications > Utilities > Terminal).
To set this to Enabled, type (or copy and paste) the following command:
defaults write com.apple.finder InterfaceLevel -string "simple"
To reset this setting to the default value, type (or copy and paste) the following command:
defaults write com.apple.finder InterfaceLevel -string "standard"
To activate this tweak immediately, type the following command, or wait until the next reboot:
Close the Terminal session by typing
exit at the prompt.
Disclaimer: Making any changes to your system can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from these modifications can be resolved. Please follow the instructions carefully and use the information provided at your own risk.