Where do webapps install after accepting them
Solution 1:
There are many ways to find this information.
1) You can find it by opening the .deb that installs them.
As an example, I pick the .deb of youtube's one from here: https://launchpad.net/ubuntu/quantal/i386/unity-webapps-youtube/2.4.10 Open it with archive manager, then look for the file DEBIAN/md5sums and open it with a text editor. It is
d5bbca2bb83fe5cc16a92e35bf75b26f usr/share/doc/unity-webapps-youtube/changelog.gz
a4b9f911211d21db51342de237b5dc5c usr/share/doc/unity-webapps-youtube/copyright
c571c6d100d418b65bcacbb4f78d46d6 usr/share/icons/hicolor/48x48/apps/unity-webapps-youtube.png
0d55340014577968398aab8fcee7409c usr/share/icons/unity-webapps-applications/128/apps/unity-webapps-youtube.png
c571c6d100d418b65bcacbb4f78d46d6 usr/share/icons/unity-webapps-applications/48/apps/unity-webapps-youtube.png
0e95c345e7aa4a96ac76a94df2c0071a usr/share/icons/unity-webapps-applications/52/apps/unity-webapps-youtube.png
a7d678d599978f9ac7bffe36d776558c usr/share/icons/unity-webapps-applications/64/apps/unity-webapps-youtube.png
58beafe67c7b136d0f157c963445c514 usr/share/unity-webapps/userscripts/unity-webapps-youtube/YouTube.user.js
5f8d5ce54c5a7c7c4cca88d5691beedd usr/share/unity-webapps/userscripts/unity-webapps-youtube/manifest.json
This are the files installed with the webapp.
2) As an alternative you can use apt-file
By using simply
$ apt-file show unity-webapps-youtube
unity-webapps-youtube: /usr/share/doc/unity-webapps-youtube/changelog.gz
unity-webapps-youtube: /usr/share/doc/unity-webapps-youtube/copyright
unity-webapps-youtube: /usr/share/icons/hicolor/48x48/apps/unity-webapps-youtube.png
unity-webapps-youtube: /usr/share/icons/unity-webapps-applications/128/apps/unity-webapps-youtube.png
unity-webapps-youtube: /usr/share/icons/unity-webapps-applications/48/apps/unity-webapps-youtube.png
unity-webapps-youtube: /usr/share/icons/unity-webapps-applications/52/apps/unity-webapps-youtube.png
unity-webapps-youtube: /usr/share/icons/unity-webapps-applications/64/apps/unity-webapps-youtube.png
unity-webapps-youtube: /usr/share/unity-webapps/userscripts/unity-webapps-youtube/YouTube.user.js
unity-webapps-youtube: /usr/share/unity-webapps/userscripts/unity-webapps-youtube/manifest.json
3) You can achieve the same by using dpkg -L
Note that this will work only if the package is already installed.
Anyhow, I don't really know how you can use this informations to kill them ;)