Need to exclude 'Forgot Password' from Google search

Greetings everyone!

I am trying to EXCLUDE the ‘Forgot Password’ link from our Google search results. The link is https://www.mydomain.com/?action=forgot

So I put this into my robots.txt file:
Disallow: /*?*

However, the “Forgot your password” link (https://www.mydomain.com/?action=forgot) still appears in our company Google search results.

Given what I’ve done in the robots.txt file is not working, what is the best approach to ensure this ‘forgot password’ link gets excluded from google search results?

Thanks for your help!