How to batch remove zero-weight vertices from vgroup? It seems that vertices with zero weight will remain in the vgroup by default, and there appears to be no straightforward way to batch remove all zero-weight vertices from it except having to manually delete one by one from Vertex Paint panel from N sidebar.

So I wonder if there are some possible ways to batch remove them from the group. Since it does lead to unexpected results when using some modifiers.

(Or is there any operators can do something like "Select by Weight"?)
It turns out that one of the existing weight tools named Clean does all I want, which offers several nice options. 

In Edit Mode or Weight Paint Mode, you can find the Weight Tools panel on the Toolshelf in 3D Viewport by pressing T.