Hey Here are the instructions to remove Delta from Firefox: Open Mozilla Firefox. Go to Tools >> Add-ons. Select Extensions. Uninstall the following extension: Delta 1.1.9 To remove Delta Toolbar. Click the small magnifier icon at the right top corner. Select Manage Search Engines... from the list. Select Search the web (Delta) and click Remove button. Click OK to save the changes. Go to Tools >> Options. Under the General tab reset the startup homepage.
i would recommend you will also check your Control Panel menu, in the Add/Remove programs to see if you have any Browserprotec or Browser Manager feature and remove it
if all of that won't help in the address bar in Firefox write: About:config confirm the upcoming message and then in the search bar write Delta and right click and reset on any iteam related to Delta