After doing some testing, I have realised I do not need

After doing some testing, I have realised I do not need the Custompress plugin (using Directory) and have deactivated and then deleted it as the Network Admin.

This deletion appears to be successful but then I realised the "Custompress" menu is still there in the admin navigation and all submenu's of it work as they did before.

I've deleted the plugin directory via ftp and still it refuses to die.

Have I missed something obvious or has the plugin evolved and become self aware?

Many thanks.