I want to delete malware pop up box
When I go to open FACEBOOK on my macbook pro it just shows a pop up box that says there may be malware on my computer and it wants me to clean it and to press next. I just exit it and do not click next. I am not so sure where this box came in from and I have no idea how to sort it out safely. PLEASE HELP.
MacBook Pro, OS X Yosemite (10.10.5)