Cut back growth so all that remains are one to two bud spurs on each arm along the cordons. Next year's vines will grow from these spurs. For areas with multiple canes clustered together ...

Cane Pruning: A vine training system in which the vine’s oldest canes ... Each surviving cane is left with a spur (a stub left by a cut cane) at its base. The canes that grow from these spurs will not ...