Can't uninstall McAfee after installing Adobe Flash Player

I need help from a technical expert.  Since I have Adblock on my desktop computer,  the square where McAfee turns up with its silly opt out-option wasn't visible at all. So now I unwillingly have McAfee on it. This seems impossible to remove, but I  HAVE to get rid  of it since I have another antivirus program.

Please help me because I  am dewperate.  I have an old desktop computer that won't even update any more, and I rarely use it.

When I try to find the program for McAfee,  I get an empty folder. But I can see it's there through Microsofts "Programs and functions (translated from Swedish). But when I try to UNINSTALL it, it says ERROR LAUNCHER.

Even in sandbox mode it says the same thing.

How do I get rid of this piece of unwanted crap? I'm very concerned it might fuss with my active antivirus program!