Simple, just use:

sudo apt-get remove unity-webapps-*appidontlike*

i.e.

sudo apt-get remove unity-webapps-twitter

Examples:

unity-webapps-amazoncloudreader - Unity Webapp for AmazonCloudReader

unity-webapps-angrybirds - Unity Webapp for AngryBirds

unity-webapps-bbcnews - Unity Webapp for BBCNews

unity-webapps-cuttherope - Unity Webapp for CutTheRope

unity-webapps-facebookapps - Unity Webapp for FacebookApps

unity-webapps-facebookmessenger - Unity Webapp for FacebookMessenger

unity-webapps-gmail - Unity Webapp for GMail

unity-webapps-googlecalendar - Unity Webapp for GoogleCalendar

unity-webapps-googledocs - Unity Webapp for GoogleDocs

unity-webapps-googleplus - Unity Webapp for GooglePlus

unity-webapps-grooveshark - Unity Webapp for grooveshark

unity-webapps-hulu-player - Unity Webapp for hulu-player

unity-webapps-lastfm-radio - Unity Webapp for lastfm-radio

unity-webapps-launchpad - Unity Webapp for Launchpad

unity-webapps-librefm - Unity Webapp for LibreFm

unity-webapps-linkedin - Unity Webapp for LinkedIn

unity-webapps-livemail - Unity Webapp for LiveMail

unity-webapps-mail-ru - Unity Webapp for mail-ru

unity-webapps-newsblur - Unity Webapp for Newsblur

unity-webapps-pandora-com - Unity Webapp for pandora-com

unity-webapps-qq-mail - Unity Webapp for qq-mail

unity-webapps-reddit - Unity Webapp for Reddit

unity-webapps-tumblr - Unity Webapp for Tumblr

unity-webapps-twitter - Unity Webapp for Twitter

unity-webapps-vkcom - Unity Webapp for Vkcom

unity-webapps-wordpress-com - Unity Webapp for wordpress-com

unity-webapps-yahoomail - Unity Webapp for YahooMail

unity-webapps-yahoonews - Unity Webapp for YahooNews

unity-webapps-yandex-music - Unity Webapp for yandex-music

unity-webapps-yandexnews - Unity Webapp for YandexNews

unity-webapps-youtube - Unity Webapp for YouTube

Each web app is its own package. I don't think any of them are dependent on each other, so you shouldn't have any issues uninstalling ones you don't need/use.

The Amazon and Ubuntu One Web Apps seem to be baked in to the web apps application, so you cannot remove these by simply uninstalling the package. The easiest way to remove these is to install Unsettings. This is a tweak tool, similar to Ubuntu Tweak. It is not available in the repos, so you have to install its PPA:

sudo add-apt-repository ppa:diesch/testing

sudo apt-get update

sudo apt-get install unsettings

Now that you installed it, fire it up and select the "Web apps" tab on the left side. To disable a web app, simply move the websites that use it from either Pre-authorized or Enabled to Disabled, then click the apply button (the little gears).