Appears to be Dog Fennel, Eupatorium capillifolium, a common perennial weed.

I believe there is now a cultivar ('Elegant Feather') for this so some people appreciate it. The seeds are very popular with songbirds in the fall so if you like to support birds, you might leave it ....

Here is a link that might be useful: Elegant feather

I had this growing in my back fence line. It is a "weed" to some, but I liked the scent of it. When it blooms in late summer it is highly fragrant and a bee magnet!