Deceptive Calendar events - Virus?

While browsing on my phone I accidentally clicked on a pop-up and have been getting event reminders about "virus on my phone" asking me to click on a suspicious link (hotrend.biz) - picture attached.

I have tried all of these actons - https://www.pcrisk.com/removal-guides/16807-deceptive-calendar-events-virus-mac - to remove this rogue calendar from my phone, however, when I click on "my calendars" I can only see my calendar and there is no option to delete the rogue account (as I can't see it) or its events.

I have noticed that there is a section "Subscriptions" - Events - if I unselect this, the annoying "virus" reminders disappear from my calendar but it still doesn't feel right. Is there any option to completely delete this off my phone?

Any advice is highly appreciated :)