InstaBack is an application developed by Ziff Davis Publishing, that allows you to automatically back up files and folders on your Windows PC. You can read more about it on the official web page. If you have the application installed on your computer and you don't need it, you can safely remove it using its uninstaller or Add or Remove Programs feature:
In Windows XP or bellow you can go to Start > Control Panel > Add or Remove Programs. In the Currently installed programs box, click on the InstaBack program and then click Remove.
If you have Windows Vista or above you need to go to Start > Control Panel > Programs > Programs and Features. Select the InstaBack application and click on Uninstall.