How to remove a Weed growing large like a tree from my flower bed

you will have to smother it out with black plastic or dig it out

cut off near where it emerges from soil...paint with straight Roundup (glysophate)....and along the remaining bark....may have to repeat in the spring ...certain "trees/weeds" are more difficult to eliminate permanently

Hi Carole. Have you tried to dig it out?

You have Giant Ragweed. I know because I had 2 and found out what they were from a Wisconsin University. I actually let mine grow because I wanted to see how big it would get (11') . Since the leaves are really prickly I wore long sleeves I cut the branches back to within 2' of the main stem. The branches are brittle so I just broke them off. I then pushed the main stem over with my foot, twisted it until it broke and then dug up the root system.

Digging it out the old fashioned way is likely your best bet!

Oh, ok, we did that in early Spring and at early Autumn it's back🙁