procedure TForm1.Test(Sender: TObject);
const ThumbForDel='0123456789ABCD'
var
  hMyStore: Pointer;
  pCertContext, pSignerCert: PCCERT_CONTEXT;
  Thumb: string;
begin
  // Open "MY" store
  hMyStore := CertOpenStore(CERT_STORE_PROV_SYSTEM, X509_ASN_ENCODING or PKCS_7_ASN_ENCODING,
                               0, CERT_SYSTEM_STORE_CURRENT_USER, PChar('MY'));
  if hMyStore=nil then begin Memo1.Lines.Add('ошибка открытия хранилища сертификатов!'); Exit; end;

  try 
      pCertContext := nil;
      repeat
      pCertContext := CertEnumCertificatesInStore(hMyStore, pCertContext);
        if (pCertContext <> nil) then begin
          pSignerCert := CertDuplicateCertificateContext(pCertContext);
          Thumb:=GetCertificateThumb(pSignerCert);
          If Thumb=ThumbForDel then begin

             If CertDeleteCertificateFromStore(pSignerCert) then Memo1.Lines.Add('Thumb '+Thumb+'Deleted');

             pCertContext := nil;
          end;
          if Assigned(pSignerCert) then CertFreeCertificateContext(pSignerCert);
        end;
      until (pCertContext = nil);
      if Assigned(pCertContext) then CertFreeCertificateContext(pCertContext);
      if hMyStore<>nil then CertCloseStore(hMyStore, 0);
    except on E:Exception do ShowMessage('Error '+#13#10+E.Message); end;
end;

             
var   hProv: WCrypt2.PHCRYPTPROV;

begin
CryptAcquireContextA(hProv,
                PAnsiChar('FAT12\BC1BBE2D_ЭЦП\pfx-57d0.000\7F77'),
                PAnsiChar('Crypto-Pro GOST R 34.10-2012 Cryptographic Service Provider'),
                80, CRYPT_DELETEKEYSET);