The Old Bailey heard how handyman Mr Thrower had been drinking and became enraged when his girlfriend Geraldine Roberts told him the youths swore, spat and threw a drink at her earlier that day.
When he confronted them, Subeir and Halliburton shut themselves in a bin chute on a first-floor communal balcony at St Dunstan's Close.
As Mr Thrower hammered with his fists on the glass partition, the 17-year-old found a 4ft long axe in a shed and Osman passed it up to Subeir, who had managed to get onto the roof of the adjoining porch.
The victim emerged from the bin chute covered in blood, staggering, holding the axe before he collapsed and died from a stab to the heart.
As the defendants ran away, Ms Roberts chased after them.
Subeir admitted striking Mr Thrower three times with the axe and Halliburton confessed to stabbing him, but both denied murder, claiming they had acted in self-defence.
