how can I stop this fake virus popup from randomly appearing in the top right hand part of my macbook screen

FalconMac wrote:

How can I delete the fake virus pop-up that randomly appears in the top right corner of my MacBook Pro screen.

I suspect you have installed adware/malware:

>System Preferences/Settings>Profiles click into it and then remove all the suspicious things from the list. (This Preference pane will not be present if no profiles found.)

also Verify you are not using SOCKS proxy:

>System Preferences/Settings>Networks>Advanced>Proxy uncheck the box [Ventura >System Settings> search “Proxy”]

Adware/malware launch daemons can set SOCKS proxies without user participation.

(SOCKS is an Internet protocol that exchanges network packets between a client and server through a proxy server.)

Adware Removal Guide—Manual removal of : http://www.thesafemac.com/arg-identification/

or

Try running this trusted utility https://www.malwarebytes.com/mac/

Effective defenses against malware and other threats… - Apple Community

Effective defenses against malware and ot… - Apple Community

Uninstall all third party apps that are Cleaners/Optimizers/VPN/Anti-Virus

all known to cause issues on the macOS