Delta Toolbar / Delta-Search / Delta-Holmes are PUPs (potentially unwanted program), that changes the homepage and default search engine of your browser, to track and send information about your browsing habits, to third party servers for targeted advertising.
You will also notice the installation of a new toolbar.
Delta Toolbar is often proposed via software affiliations systems. After every successful installation, the author is paid.
Pay attention to what you download and download sources.
These software are not essential and slow your computer.
Step 1- Removal via the Control Panel
For Windows Vista/Seven/8: Go to the Control Panel and then Programs and Features, look and uninstall Delta Search/Delta Toolbar.
For Windows XP: Go to Control Panel, then Add/Remove Programs, find and uninstall Delta Search/Delta Toolbar.
Reset your browser settings:
Remove the related extensions added to Firefox or Google Chrome.
Change your default search engine.
Reset your homepage.
You can also try using AdwCleaner or Malwarebytes' Anti-Malware software.