PLEASE tell me how to remove Quicklook PI?

Some piece of Malware / Adware may have been installed.

Suggest downloading from a Trusted Developer and Respected ASC Contributor the application Malwarebytes for Mac. It is free or paid for added features. Run the Application and it should remove the malware / adware. Once done, restart computer and test.

There are no known Viruses in the wild that self replicate and affect macOS. There are Malware and Adware that does affect macOS and are often times downloaded as part of an Application from Third Party UnTrusted Site and get installed along with the Application.

You are Very Welcome and Thank You Too :-))

Do come back to the ASC Forums if or when additional questions / concerns arise. Plenty of Contributors willing to assist or answer questions.