Is there a certain type of connector needed for the ABS block end and the flexible hose end?

The flaring tool arrived and I have been practising with it. I hit a snag when removing the old brake line. It looked as if someone had had a go previously as the nut looked a bit chewed and the 11mm spanner had no resitance. If have been trying with the 10mm end and a mole wrench with no luck and have probably made it worse. Is it possible to get the flexible hose off with the brake line attached?