The form helta- in the Etymologies is a misreading according to VT/46:14
Noldorin
ada
noun. father (hypocoristic), father (hypocoristic), [G.] daddy
ada
noun. father, daddy
adar
noun. father
adar
noun. father
a
conjunction. and
ar
conjunction. and
heltha-
verb. to strip
A hypocoristic (affectionate) word for “father” in The Etymologies of the 1930s, hence roughly equivalent to English “daddy”, derived from the root ᴹ√ATA “father” (Ety/ATA).
Conceptual Development: A similar set of affection words appeared the Gnomish Lexicon of the 1910s: G. ada or nada, adi or nadi (GL/17, 59).