I ended up somehow with Bitdefender trial being installed on my MacBook. I never used it and when I did my weekly scan Malwarebytes detected and removed it but every morning I have a pop up saying "Your System may be at risk! Please scan your system and protect your Mac from all the threats." It gives me two selections CLOSE or IMMEDIATELY SCAN and I have tried both with no response (thinking if I can bring up the program I can eradicate the pop up), have emailed BitDefender to no avail and looking into library or simply trying to spotlight anything which may be hidden brings up nothing. No extensions installed either but I wonder if someone has a trick to reveal and delete this annoying pop up?