In Tree Sloth I don't have a cull branch component (but that's a really good idea for a new one) but you can use "Divide Branch" to assign an index pattern for outputting branches into two streams.

http://www.grasshopper3d.com/group/milkbox/forum/topics/tree-sloth

If you're not a member of milkbox, the gha is attached...

I am looking for the cull branch component as well. I've run a boolean test to see if my shapes are inside a brep. I need to maintain the branch structure keep the grid working properly. I tried using the 'Member Index' component and the 'Find Similar Member' component to no avail. I was thinking I could compare the branch members I've extracted against the original grid to get their index values and then use 'Cull Index' to return my cleaned up grid. The 'Tree Branch' component returns the exact opposite of what I need.

After wording the issue, I realized the logic could be slightly adjusted to get the desired intent. I was just looking at in the wrong way. You can see the adjusted solution below: