Dead head when the flowers go over to keep it flowering. If you wish you can give it a trim in the autumn to tidy it up and remove any dead wood.
Buddleia davidii flowers on new growth made in the current year, so in Early spring cut back lasts year’s growth to about 12" from the base and leave a cluster of stems, avoid cutting back into older wood, mulch and feed as well.

They are very tough plants and you can give it a bit of a trim and tidy up now if you need to.The main pruning is normally done in spring.

I used to hack mine back whenever I wanted. If you do this just before they flower you're cutting the flowers off, but at least you can still get past it! You CAN'T kill it, no matter how hard you prune it.

i completely hacked mine down a few weeks ago as it was about 15ft high so i cut it right down to a 6" stump now new shoots are appearing all round the base.

Thankyou very much, :) ime going to do some hacking right now,as i cant see my house! :)

Whistle if you get lost lol!

I'm sure it will be all the better for it. Like Sensei, I used to cut mine right down to the ground every year after it grew too enormous. Yours will be fine.

I cut mine down to 4' in the autumn because we are in a very windy situation and they tend to split if I do not then back to 1' in the early spring. Mine will not flower until August. Then they will be covered in bees and butterflies.