You're trying to log in to an event, and it keeps telling you the magic link is expired? Perhaps, you've typed in the wrong email address when registering and would like to change it, but the site keeps defaulting to the old one. Clearing your cookies will help you get a fresh start.
Clearing up your cookies would depend on the browser you're using.
On Google Chrome
Navigate to Chrome> Clear Browsing Data.
Or you can use the following commands- Cmd+Shift+Delete on a Mac and Ctrl+Shift+Delete on a PC.
Navigate to Safari> Preferences
Click Privacy and select Manage Website Data
You can select the websites you'd like to clear or choose to Remove All.
To clear out cookies using a Mozilla Firefox browser, here's the article from their support website.
For Microsoft Edge, here's the article from their support website.
If you have issues, please don't hesitate to reach out to firstname.lastname@example.org.