A. Applications typically store information in your profile and in other areas of the file system and registry. Some changes made to your profile by virtualized applications persist as part of your standard profile, so deleting the virtualized application from your OS won't affect the settings. Other changes applications make are identified as user-specific during the sequencing of the application, such as a custom dictionary or toolbar changes in Microsoft Office, are stored in a separate package file on your machine that's unique for each virtualized application. This package isn't deleted when you delete a virtualized application from your machine, so customizations are maintained for when the application is executed again.
App-V creates a folder for each virtualized application that has custom changes under the %USERPROFILE%\AppData\Roaming\SoftGrid Client\<application-GUID> folder. For example, for my account and virtualized PowerPoint I see a folder named C:\Users\john.SAVILLTECH\AppData\Roaming\SoftGrid Client\POWERPNT.V12-7F424220-BD7D-4D8C. Within this folder is a file that represents the stored changes that were captured by the virtualization engine that otherwise would have been written to the file system. You'll see a file, UsrVol_sftfs_v1.pkg, that represents all the user specific data and configurations for the application. Note that because this package is stored under your roaming profile area, as long as you've enabled roaming profiles, the virtualized application settings will follow your user logon wherever you use the virtualized application.
If you want to delete your user-specific customizations and data for the application, instead of deleting the application within the App-V client, select Clear. The user-specific pkg file for the application will be re-created the next time you execute the virtualized application.
For more information about how App-V uses your disk space, check out this TechNet blog, which is a great overview.