how do I block mcafee pop ups?

Hello, To stop These fake popups from showing in firefox, first go to menu > settings > privacy & security, then scroll down to permissions, and find the notifications section. After that, click the settigns button next to it, and look through the list of any unfamiliar websites and remove them. Next, Enable Firefox's built in popup blocker. To do so, go back to "permissions", and check "block pop-up windows" is checked. If these popups are persistent, try running a malware scan in windows defender.