Removing interception certificates via Fiddler options "Remove Interception Certificates" only removes them from Personal and Trusted Root Certification Authorities of the Local Computer Store.
Certificates located in Current User Store - Trusted Root Certification Authorities and Intermediate Certificates is not removed.
This certificate is not trusted after using "Remove Interception Certificates" and has status "This CA Root certificate is not trusted because it is not in the Trusted Root Certification Authorities store".
sigcheck -t[u]v doesn't show any warnings.
Tested this on both Windows 7 and 10.
Tried refreshing certmgr, restarting it, and rebooting machine with no success - certificates are still there.