Q: Help to remove offers4u ads

I'd recommend using Malwarebytes free tool for removing adware. (Previously adwaremedic)

You can find it here

Let me know if this is able to get rid of the ads.

Hi shyshine, force Quit Safari ( command + option + esc keys). Then restart Safari holding the Shift key. If you still have problems Empty Caches (Safari menu > Preferences > Privacy > Remove all website data. (This will also remove history.)

Stop pop-up ads in Safari - Apple Support

Safari – Popup takes over

Popup remover – Scam Zapper

You will have t do this after starting up in Safe Mode to prevent adware

from interfering with the removal of adware .

1. Shut down the computer.

    Press the power button. Immediately after you hear the startup sound,

    press and hold the Shift key.

    The Shift key should be pressed as soon as possible after startup,

    but not before the startup sound.

    Release the Shift key when you see the Apple logo on the screen.

    Startup will take longer than usual.

    Screen flickering is normal in Safe Mode.

    Login to your account. Launch Safari.

    Enter this address       https://www.malwarebytes.org/antimalware/mac/

    in the Safari address bar.

    Download,   Install , open,  and run it by clicking “Scan”  button   to remove adware, if present.

    Once done, quit MalwareBytes.

2. Safari > Preferences > Extensions

    Turn all extensions off

     or  uninstall all extensions you haven’t installed knowingly.

3. Safari > Preferences >  Search > Search Engine :

    Select your preferred   search engine.

4. Safari > Preferences > General > Homepage:

     Set your Homepage.

5. Restart normally from  menu in the menu bar.