Here are some ubuntu linux commands to add and remove repository/software sources and applications.
Add application
sudo apt-get install {package-name}
Eg: Adding skype-wrapper application
sudo apt-get install skype-wrapper
Remove application
sudo apt-get remove {package-name}
Eg. Removing skype-wrapper application
sudo apt-get remove skype-wrapper
Eg. Removing application package called skype-wrapper along with all configuration files
sudo apt-get –purge remove skype-wrapper
Add Repository
sudo add-apt-repository {repository}
Eg: Adding skype-wrapper’s source/repository
sudo add-apt-repository ppa:skype-wrapper/ppa
Then update with
sudo apt-get update
Remove repository
sudo apt-add-repository –remove {repository}
Eg: Removing skype-wrapper’s source/repository
sudo apt-add-repository –remove ppa:skype-wrapper/ppa
Then update with
sudo apt-get update