Go to Start > Control Panel > Programs & Features (or Add/Remove in XP) > Looks for unfamiliar (or unknown) programs, right click & uninstall (follow a prompts).
Open a browser you installed (Internet Explorer, Firefox, Chrome, Opera, Safari) > go to Add-ons or Extensions (in Firefox) > locate unfamiliar (or unknown) > remove it.
Open a browser you installed (Internet Explorer, Firefox, Chrome, Opera, Safari) > go to Tools or Settings (or similar) and reset browser settings to default.
To remove remnants of adware in PC, install Malwarebytes Anti-malware (free version) http://www.malwarebytes.org/products/malwarebytes_free/ and install, update and run the free version – just go with default options in the prompts. If malware blocks/ prevent you to install malwarebytes, rename the malwarebytes installation file to somethingelse.exe or something similar. Once installed, do a quick scan, it’ll detect all known viruses & remnants of adware (reboot, if prompts).
How to get rid of unwanted popups?
Common Virus or Malware infection Prevention Steps
Common sources of virus infections are peer to peer software being used incorrectly, and downloading things from un-trusted sources like unfamiliar website. Avoiding these two things will greatly reduce your risk of infection.
Avoid installation of unnecessary programs or add-on’s (for example, Internet toolbars or file-sharing programs). Unnecessary software may impact system performance, contain malware, and/or cause conflicts with applications that perform similar functions.
Do a little researching any unknown programs in your favorite search engine prior to installing them.
Be cautious of all web browsing and Internet downloads, many unfamiliar websites may infect your computer/ drop adware type malware through drive-by download technique without your knowledge.