Hi Jennifer, the main step when removing portalsepeti.com browser hijacker is removing it's entries from Internet browser shortcut targets.

For Internet Explorer:

Locate the Internet Explorer shortcut on your Desktop and click the right mouse button over it. In the opened menu, choose "Properties". In the opened window, locate the Target field and eliminate text (hxxp://www.portalsepeti.com/...), which is entered after "C:\Program Files\Internet Explorer\iexplore.exe".

For Mozilla Firefox:

Locate the Mozilla Firefox shortcut on your Desktop and click the right mouse button over it. In the opened menu choose "Properties". In the opened window locate the Target field and eliminate all text (hxxp://www.portalsepeti.com/...), which is entered after "C:\Program Files\Mozilla Firefox\firefox.exe"

For Google Chrome:

Locate the Google Chrome shortcut on your Desktop and click the right mouse button over it. In the opened menu, choose "Properties". In the opened window, locate the Target field and eliminate all text (hxxp://www.portalsepeti.com/...), which is entered after "C:\Program Files\Google\Chrome\Application\chrome.exe"

After following these steps you might also want to scan your computer with Malwarebytes Antimalware and Spyhunter (portalsepeti.com might be not the only adware/browser hijacker that installed on your computer).