Looks like a Buddleia which grow anywhere, even roofs and guttering! If you like it, leave it as it has flowers which attract butterflies and bees. If it's likely to get under foundations or drains it might be better to take it out. No doubt someone else will make suggestions.

yes it is a buddleia but as it is against the wall I would advise removing it as the roots may well compromise it.
the seed is very light and slightly winged so they are dispersed by the wind. many are a pale lilac and are B davidii. if you want to keep it then plant it in a sunny border. water well if you do move it.
Going by its size it would have been there last year as it seems to have some woody parts to the stems.

If you want to keep it it'll grow well in a pot too & bees will love it. Better if it's pruned down to above a leaf joint to make it compact & bushy in a container

Thanks for the replies, really appreciated. I guess I'll try and replant it somewhere else if I can get it dug up. It does seem to have some woody stem there but I never noticed it last year. My son's property, three quarters of an acre, which was relatively unkempt when he moved in, although signs that at some point it had been well cared for, and I'm just learning what does and does not grow. THanks again.