How do I remove security certificate exceptions from Google Chrome?

I've finally found the answer.

On the address bar, click on the padlock to show the certificate details. In the Connection tab there is a button "Stop using this certificate". Click it to remove the exception.

Chrome looks a little different these days, so here's an updated picture of where to re-enable the warnings.

You still begin by clicking the "Not secure" indicator to the left of the URL. Then, in the panel that pops up, you click the "Re-enable warnings" link.

01/2017 - After many Chrome updates, now you just click to the left of the URL, where the padlock is, or if something else (mine is a local server, displaying a "red triangle Not secure"), click that to display the information about the connection, then click "Re-enable warnings"

To "Re-enable warnings" for all SSL warnings if you don't want to clear your history (or if you dont know all the exemptions you have in place), you can close Chrome and edit: "C:\Users\USER\AppData\Local\Google\Chrome\User Data\Default\Preferences" and set ssl_cert_decisions":{},"

Stored in the JSON-path:

profile > content_settings > exceptions > ssl_cert_decisions

Or you can change the decision_expiration_time of the specific exemption to be equal to the last_modified time

Example: "ssl_cert_decisions":{"https://expired.badssl.com:443,*":{"last_modified":"13235055329485008","setting":{"cert_exceptions_map":{"-201cgaDTf2DD6Cj0N6/tKvudkzDuRBA3GwKd8T9hE7mHhQ=":1},"decision_expiration_time":"13235055329485008","version":1}}}

In case the HTTPS URL triggers a 301/302 redirection to an HTTP URL, the methods described above won't work since the browser immediately redirects to a non-secure page which doesn't include the padlock button (as pointed out by Alex in the comments).

In this case, it's possible to work around this problem by disabling redirections for the website: Settings -> Advanced -> Site Settings -> Pop ups and redirects -> Block -> Add -> Add the URL -> Visit the URL -> Disable the exception according to the accepted answer -> Remove redirection block.