A verb in The Etymologies of the 1930s glossed “strip” derived from primitive ᴹ✶skelta- under the root ᴹ√SKEL (Ety/SKEL; EtyAC/SKEL). In The Etymologies as published in The Lost Road Christopher Tolkien gave the form as helta (LR/386), but Carl Hostetter and Patrick Wynne corrected this to heltha in their Addenda and Corrigenda to the Etymologies (VT46/14). According to Hostetter and Wynne the original form was haltha- “strip” from ᴹ√SKAL until Tolkien decide this A-root meant “screen, hide” instead.
Conceptual Development: In Tolkien’s earlier writings he had a number of other words of similar meanings. The Gnomish Lexicon of the 1910s had G. daf- “strip, flay, peel skin” and G. dautha- or dauthra- “strip” (GL/29). It also had G. {falta- >>} faltha- “strip, despoil, rob, make bare” based on the early root ᴱ√fal- (GL/33), and G. pasta- or padhra- “skin, peel, flay”, probably based on the early root ᴱ√PARA [PAÐA?] (GL/63; QL/72). The Gnomish Lexicon Strips had {dautha- >>} dawtho “to flay” (PE13/112), while Early Noldorin Word-lists of the 1920s had ᴱN. gwath “to strip” (PE13/146).
Neo-Sindarin: For purposes of Neo-Sindarin, I would extend the use of heltha- to cover all of these earlier meanings: “to strip, ✱flay, peel skin”, and by extension “✱to despoil, make bare”.
An earlier name for S. Deldúwath appearing in Silmarillion drafts from the 1930s, glossed “Deadly Nightshade” (LR/133) or “Night of Dread’s Shadow” (LR/406). It is a combination of gwath “shade”, fuin “night” and Daedhelos “Shadow of Fear”.