How to uninstall isc-dhcp-server

To uninstall isc-dhcp-server just follow these instructions.
 Uninstall just isc-dhcp-server: sudo apt-get remove isc-dhcp-server 
This will remove just the isc-dhcp-server package itself.

 Uninstall isc-dhcp-server and it's dependencies: sudo apt-get remove --auto-remove isc-dhcp-server This will remove the isc-dhcp-server package and any other dependant packages which are no longer needed. 

Purging your config/data too If you also want to delete your local/config files for isc-dhcp-server then this will work. 
Caution! Purged config/data can not be restored by reinstalling the package.
sudo apt-get purge isc-dhcp-server 
Or similarly, like this isc-dhcp-server
sudo apt-get purge --auto-remove isc-dhcp-server

Configure a Squid proxy server through Webmin n Your Squid cache directory /var/spool/squid3 has not been initialized

By Jack Wallen in SMB Technologist Setting up Squid The first thing you will see is the error "Your Squid cache directory /var/spool/squid3 has not been initialized. This must be done before Squid can be run." In order to initialize this, click the Initialize Cache button (with either an existing user, or you can create a new user/group "proxy"). At this point you will see the "Stopping Squid" warning. Once the system has been initialized, you will be prompted with the Return To Squid Index link. If you continue seeing this error, here's what you need to do: Open a terminal window. Open the file /etc/squid3/squid.conf. Search for the line #cache_dir ufs /var/spool/squid3 100 16 256 (around line 2245). Remove the "#" character. Save the file. Go back to Webmin and click the Initialize Cache button again. Your plan for using the proxy will dictate how you configure it. Regardless of how you use it, you will want to define the ports used by the proxy first. By default, Squid uses 3128. You can stick with the default, or if you need to go with a non-standard port.