ctrl + t {for terminal prompt}

cd /etc/NetworkManager/system-connections 

sudo rm {wireless_hotspot_name}

Hope that helps

EDIT FROM ONE YEAR LATER

Seems like this turned into a fairly popular answer, so I went ahead and wrote an automated script to do this for everyone. Just copy the below script into into /usr/local/bin/wireless and remember to run command sudo chmod +x /usr/local/bin/wireless

Glad to see this is continually helping fellow *buntu users ;)
newest version(s) will be on GitHub

#!/bin/bash

# Review and Remove Wireless Access Points on DEB based Systems

# Make sure to place script in /usr/local/bin 



# CPR : Jd Daniel :: GabelBombe

# MOD : 2013-12-09 @ 12:27:02



# INP : $ wireless -{flag} {arg}



##===============================================================##

##===============================================================##



clear



# If the user is not root

if [ "$(id -u)" != "0" ]; then

  echo "This script must be run as root" 1>&2 ; exit 1

fi





declare -r VERSION='1.2b'

declare -r net_dir='/etc/NetworkManager/system-connections'





function list ()

{

  cd "${net_dir}"



    export count=$(ls |wc -l) # used in drop function



  files=$(ls) # simple ls



  echo -e "

	Found ${count} wireless connections"



    for f in $files; do

        echo -e "	 * $f"

    done

}



function drop ()

{

  # make sure that we have a working file and directory...

  cd "${net_dir}" ; [ -f "$OPTARG" ] || { echo -e "

	Connection does not exist..." ; exit 1; }



  # confirmation for removal

  printf "

	Do you want to delete $OPTARG [y/n] " ; read -r resp



    # strtolower, and rm

    if [ 'y' == "$(echo $resp | awk '{print tolower($0)}')" ]; then

      rm -f ${net_dir}/${OPTARG}

    fi

}



function flush ()

{

  # make sure that we have a directory with files...

  cd "${net_dir}" ; list ; [ 0 -ge "${count}" ] && { echo -e "	Exiting, Nothing to flush..." ;  exit 1 ; }



  # confirmation for removing all files

  printf "

	All Wireless Connections will be removed, continue? [y/n] " ; read -r resp



    # strtolower, and rm

    if [ 'y' == "$(echo $resp | awk '{print tolower($0)}')" ]; then

      rm -f ${net_dir}/*

    fi

}



function version ()

{

  echo -e "

	wireless (GNU wireless network purge) v${VERSION}"

  echo -e "

	Copyright (C) 2013 Hydra Code, LLC."

  echo -e "	License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.

	This is free software: you are free to change and redistribute it.

	There is NO WARRANTY, to the extent permitted by law."

  echo -e "



	Written by Jd Daniel (GabelBombe) http://github.com/GabelBombe"

  exit 0

}



function help ()

{

  echo -e "

	Usage: wireless [OPTION]... [FILE]..."

  echo -e "	List, remove single or flush the contents of your Wireless Network Manager"

  echo -e "

	The options below may be used to perform the above actions, this program will only"

  echo -e "	run a single flag or parameter at a time. Flag chaining is only available for -d"

  echo -e "	  -l, --list 		 List the contents of your 'Network Manager'"

  echo -e "	  -d, --drop [conn] 	 Drop a single (or multiple) wireless connections"

  echo -e "	  -f, --flush 		 Flush all wireless connections."

  echo -e "	      --help 		 Display this help menu and exit"

  echo -e "	      --version 	 Display version information and exit"

  exit 0

}



##===============================================================##

##===============================================================##



# no long-opts supported except --help

while getopts ':ld:f-:' OPT; do

  case $OPT in



    l) list  ;;

    d) dirList="${dirList} $OPTARG" ; drop  ;;

    f) flush ;;

    -) #long option

       case $OPTARG in



          list)     list    ;;

          drop)     drop    ;;

          flush)    flush   ;;

          help)     help    ;;

          version)  version ;;



       esac

   ;;

    : ) echo -e "

	Missing option argument for -$OPTARG" >&2;               exit 1;;

    * ) echo -e "

	Unknown flag supplied ${OPTARG}

	Try wireless --help"; exit 1;;

  esac

done



shift $(($OPTIND - 1))



##===============================================================##

##===============================================================##