Select the group you wish to delete entries from. In the "Files to backup" window, highlight a file by clicking on it. Click the Delete Entry button. You will be prompted for confirmation. The entry for the file will be deleted from the group, the original file will not be deleted. You can also drag the file and drop it on the Delete Entry button. Multiple selections are also allowed. The delete confirmation can be turned off and you can choose to delete the entry from the previous backup, or leave it in place, from the backups menu.
Select the group you wish to delete and click the Delete button. You will be prompted for confirmation. The group will be deleted from your group list and you will be asked if you wish to also permanently delete the zip file for that group. Choosing 'no' will send the previous backup file to the recycle bin, choose 'yes' and the file will be permanently deleted. The original files will not be deleted.