If you signed in to your gmail account with 2-Step Verification on someone else’s computer, and you by mistake check off the box “don’t ask again on this computer”, how to you force 2-step verification again on that computer. The answer is that you need to tell google to revoke 2-step verification for that device. It has nothing to do with the browser you are using. Deleting cookies will not help.

Remove computers & devices from your trusted list

1. Go to your Google Account. You might need to sign in.
2. Under “Sign-in & security,” select Signing in to Google.
3. Choose 2-Step Verification.
4. Under “Device activity & security events,” there is a box called “recently used devices” click Review Devices.
5. Select the computer or device you want to remove, then click Remove

NOTE: You can’t remove the computer you are currently using.