how to remove "Trojan virus detected" pop-up

Hi Ambaysinger,

You may want to check out this question which describe similar issue as what you're having. Hope that helps!

If the "Trojan virus detected" message appears inside your browser rather than from your antivirus software, it's often a scam notification generated by a website. Try closing the affected tab, clear your browser's cache and site permissions (especially notification permissions), and run a scan with a trusted security program to rule out any real threats. If you can share which browser and operating system you're using, it will be easier to suggest the right steps.

how to remove "Trojan virus detected" pop-up How to remove system has been infected click here to remove

Are these as small poups on bottom right corner of Firefox window.?. If so then these may just be web push notifications from sites you have allowed to send you notifications. Instead of useful information some may send you spa, fake virus/tojan alerts etc. You can revoke the sites from sending you notifications.

https://support.mozilla.org/en-US/kb/push-notifications-firefox#w_how-do-i-revoke-the-notifications-permission-for-a-specific-site