Should I pinch out scarlet wisteria or just let carry on as it is a tree

Hi, I wouldn't prune it at all yet, it's still too small, it's pruning group 9, which means it should only be lightly pruned, to maintain symmetry, it isn't related to Wisteria, its a Sesbania punicea, which as you know, needs a minimum winter temperature of 41f, best grown in a warm greenhouse, in loam based compost, it is classed as a large shrub or small tree, growing to about 6 to 12 ft high, and a spread of about 5 to 8 ft, Derek.