SafeCopy will never remove files from your backup automatically. So even if you delete a file from your local computer, it will not be deleted from your backup. This allows you to intentionally clear off things from your computer knowing you have an archive online in your SafeCopy account.
You can manually remove files and folders from your account via the web console. Use the Browse tab to navigate to the folder or file you want to delete and select "delete" from the blue drop down arrow in the corner. For larger folders, it may take a couple minutes for the process to complete.
You may also delete an entire computer from your online backup using the same method.
If you ever want to remove everything in your account to start fresh, visit the article how to reset your account.