how to get rid of http://lkysearchds4407-a.akamaihd.net/ps?

You have adware/malware installed. Download this program which was written by Thomas Reed, a long time poster. The program will search for malware/adware The program will do the work for you which makes it easy. It may be necessary to run more than one scan. After scanning a couple of times, restart the computer and test.

 Malwarebytes Anti-Malware for Mac      10.10 and later

Also check Safari/Preferences/General to see what is set as the Home Page.

Safari Homepage setting greyed out 

   1. Remove unknown profiles if present.

      System Preferences > Profiles

      Open System Preferences, click the “Profiles” icon ( a checkmark on a gear) .

      When Profiles pane opens, select the unknown profile and click the minus button at the bottom.

  2. Remove unknown extensions:  Safari > Preferences > Extensions

      https://support.apple.com/guide/safari/use-safari-extensions-sfri32508/mac

   3. Check for adware.

       Run the latest release of Malwarebytes for Mac to remove malware/adware, if installed on your Mac.

       For instructions:  Install Malwarebytes for Mac          Uninstall Malwarebytes for Mac

       Click the “Scan Now” button. Once done, quit Malwarebytes for Mac.

       Restart the computer and relaunch Safari holding the shift key down.

       Additional steps if necessary.

  4. Reset search engine:    https://support.apple.com/guide/safari/customize-your-search-ibrwe75c2a3c/mac

  5. Reset  Homepage.   https://support.apple.com/guide/safari/set-your-homepage-ibrw1020/mac 

Homepage reset: Credit thomas_r

https://discussions.apple.com/thread/8323739?page=2

  6. Restart your Mac. Relaunch Safari holding the Shift key down.