You can prune but it will grow again very rapidly

Prune as you would Buddleja davidii but leave it until early April this year as the weather now is too cold and the new shoots could be damaged.

i reduce mine by half in the autumn to keep it tidy over winter and then again about now. I find in a warmer winter it tends to keep its leaves too. Mine has never been as compact as the davidii type though.

Good advice, to reduce the height over winter as it prevents wind rock. B.x weyeriana Sungold can be treated exactly as a larger B. davidii cultivar. Although about half B. globosa genetically it takes after B. davidii more in everything except flower colour and shape.

Davidii comes in all sizes from true compact forms like 'White Ball' at about a metre up to small trees like 'Black Knight' (if left unpruned).