I would take these pictures in as you have done here to a local gardening store or a tree expert to get their opinion to be sure what it might be, and how to proceed.

We have always had when there are 6-12 evenly paired leaves with one at the end growing out, branched as these are, as being a type of sumac tree; some being regular, harmless trees, but others are poisonous and should not be touched without gloves, long sleeves and pants on (completely being covered) and with using tools to cut back or out. There are also sumac root killers so they don't come back. So proceed with caution before trying to remove them if considering it. Please be sure to identify it first. If it does turn out to be poison sumac, and you decide to remove it yourself, which is easy to do, just be sure the clothes, gloves, and tools should be treated afterward with something like Tecnu (available at pharmacies) to strip the oils off of them.

Hopefully it is a regular sumac, they can be really pretty in the fall, or perhaps something even more harmless.