Can I remove weights/vertex groups for specific vertices? I have done a rough head swap on a model. Tilting the head side to side makes my neck kind of protrude from my body and clip into the body and necklace. The problem is that that the bottom half of the neck is animated or weighted or whatever, and I'd rather it not be, I'd rather it just stay stationary.

In short, the thing I want is for the top half of the neck to stay animated and the bottom half to be still. Any help on how to do that? I have no idea how to make vertex groups or weight paint, etc.
Remove vert(s) from vertex group.

In edit mode, select the verts you want removed from group. Click the remove button on the Vertex Groups Edit Panel to remove from the active group.

Here is a sample where all the vertices of the default cube are added to the "Group" group.  The bottom face is selected and its verts removed from the group.  I've turned on the show weights in the mesh display panel to make visualizing the group easier.