Step One: While on the user's profile, click Finder on the dock, and click Go in the top menu bar.
Step Two: Next, hold down the option key and the Library folder will appear under the Go menu.
If the Library folder does not appear while holding down the option key, head over to MACINTOSH HD- Users-User-LIBRARY.
Step Three: Look for the Keychains folder and open it.
Step Four: Highlight all the items in the Keychains folder and move them to the trash.
Step Five: Empty the trash. (If you get an error that the login keychain is in use, restart the Mac and the trash will be able to be cleared after the reboot.)
Step Six: Restart the machine, log in to the user account and select “Create new Keychain” if prompted.