I decided to have a look and see what I could find out about this.
How did potentially unwanted applications install on my computer?
PUAs are distributed via download/installation set-ups of other products. This deceptive marketing tactic of packing regular software with unwanted or malicious additions is called "bundling".
Rushing download/installation processes (e.g. ignoring terms, skipping steps and settings, etc.) increases the risk of inadvertently allowing bundled content into the system.
Some PUAs have "official" download sites. Intrusive advertisements proliferate these applications as well. Once clicked, they can execute scripts to download/install PUAs without users' consent.
How to remove fake pop-ups?
In most cases, pop-up scams do not infect users' devices with malware. If you encountered a scam pop-up, simply closing it should be enough. In some cases scam, pop-ups may be hard to close; in such cases - close your Internet browser and restart it.^
In extremely rare cases, you might need to reset your Internet browser to default settings.