Restrict available command options in AuCTeX

I’m using AuCTeX (v.11.89.6 with Emacs 25.1). I have no problems with it, just a small nuisance. Whenever I use TeX-insert-macro (C-c C-m) I get many options I never use. For instance, when I wish to insert the command enquote{...}, I run TeX-insert-macro and start typing enq. The first option I get is MakeHyphenQuote and so I have to scroll down to select enquote.

To go around this issue, I used to edit the csquotes.el style file and remove MakeHyphenQuote from the list. However, each time AuCTeX updates itself, my file is removed and all customisation gets lost.

I also tried editing the TeX-symbol-list variable (which, according to apropos-value, seems to hold these commands), but couldn’t make it to work.

So my question is whether I can remove MakeHyphenQuote (or any other command or environment) from the list used by AuCTeX for command insertion.

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Update: just to clarify, I’m using ivy-mode.

(defun nv/cleanauctex ()
  "Removes two elements from TeX-symbol-list"
  (interactive)
  (setq TeX-symbol-list (remove '("MakeHyphenBlockQuote" "Language" "Opening quotation mark" "Delimiter for citation" "Closing quotation mark") TeX-symbol-list))
  (setq TeX-symbol-list (remove '("MakeHyphenQuote" "Babel's language name" "Opening quotation mark" "Closing quotation mark") TeX-symbol-list))
  )