Go to the "Common Application" website and log into your account using your user name and password under the "Apply" section on the page.
Select the "My Colleges" tab and remove all the schools in your account by clicking the "X" button located next to each school. Select "Yes" to each confirmation that appears asking if you are sure you want to delete the college from your college list. By deleting the colleges from the list, the college will not be able to view you as an "in-progress" applicant or communicate with you via email or telephone about your application.
Wait until the end of the application season for your Common Application account to be terminated. Application season ends during the summer, which means your account will be automatically canceled around early- to mid-June.