How to Get rid of “Chapter N” without ruin the fontsize, and Remove the numbering “N title chapter” on the TOC

Question

Actually i have seen all possibilities similar questions one by one. They have similar problem, but my problem is more complicated. So, here is my problem:

I want to remove "Chapter N" when i'm using:

\chapter{\textbf{Test Chapter}}

I'm not going to use \chapter*{...} because this makes my section start with 0.1 Section instead of 1.1 Section. I have seen this link, and tried to use it using \titlesec to remove my Chapter N.

This is my code before i changed anything, (Btw, i wrote the important part of my code only so you can focus on it):

\documentclass[a4paper,12pt,oneside,openany]{book}
\usepackage{titlesec}
\titleformat{\chapter}[display]
    {\normalfont\bfseries\centering}
    {\chaptertitlename \thechapter}{12pt}{}
\titlespacing*{\chapter}{0pt}{10pt}{10pt}

This is my code after i tried to remove Chapter N:

\documentclass[a4paper,12pt,oneside,openany]{book}
\usepackage{titlesec}
\titleformat{\chapter}[display]
    {\normalfont\bfseries\centering}{}{0pt}{\Large}
    {\chaptertitlename \thechapter}{12pt}{}
\titlespacing*{\chapter}{0pt}{10pt}{10pt}

and actually it removes the Chapter N like i wanted before. The point is, i only adding {}{0pt}{\Large} after {\normalfont\bfseries\centering}. And because of this, i got 2 problems here:

First Problem:

My fontsize was changed and getting bigger, and i got error message refers to {\chaptertitlename \thechapter}{12pt}{}

You can see before and after removing Chapter N in the following link below:

BEFORE REMOVING CHAPTER and AFTER REMOVING CHAPTER

This is my error message: link image Even though i\ve tried to place after \begin{document}

My Goal is i can remove Chapter N using simple code, without any error messages, and not changes the fontsize that i've changed before that is 12pt.

Second Problem:

This is not actually a problem that i got after using my code as i said before, i mean it's another problem and i want to remove numbering N title chapter on the TOC. Here is my current output. As you can see, there is a number in the front 1 BAB. 1 PENDAHULUAN and i want to remove 1 on the front becomes BAB 1. PENDAHULUAN like this output.

I really appreciate your answer. Please help me and Thanks in advance.

EDIT: This is my MWE

(Main tex file)

\documentclass[a4paper,12pt,oneside,openany]{book}
\usepackage{pgf, tikz}
\usepackage[a4paper, inner=4cm, outer=3cm, top=4cm, bottom=3cm]{geometry}
\usepackage[onehalfspacing]{setspace}
\usepackage{fancyhdr}
\usepackage{titlesec}
\usepackage{setspace}
\usepackage[titles]{tocloft}
\usepackage{tocbibind}
\usepackage{indentfirst}
\fancyhf{}
\cfoot{\thepage}
\linespread{1.5}
\pagestyle{plain}
\renewcommand\cftchapdotsep{\cftdotsep}
\titleformat{\chapter}[display]
    {\normalfont\bfseries\centering}
    {\chaptertitlename \thechapter}{12pt}{}
\titlespacing*{\chapter}{0pt}{10pt}{10pt}

\renewcommand{\contentsname}{DAFTAR ISI}
\renewcommand{\listtablename}{DAFTAR TABEL}
\renewcommand{\listfigurename}{DAFTAR GAMBAR}

\addtocontents{toc}{\protect\null\protect\hfill{Halaman}\protect\par}
\setlength\parindent{1.25cm} 
\begin{document}

\clearpage
\thispagestyle{empty}

\frontmatter %

\pagestyle{fancy}   
\renewcommand{\headrulewidth}{0pt}
\include{cover1}
\include{cover2}


\mainmatter %
\include{bab1}

\end{document}

(File: bab1)

\chapter{\textbf{BAB 1. PENDAHULUAN}} 
%TEXT HERE
\section{Latar Belakang} 
%TEXT HERE

Answer 1

Change

\titleformat{\chapter}[display]
    {\normalfont\bfseries\centering}
    {\chaptertitlename \thechapter}{12pt}{}

to

\titleformat{\chapter}[block]
    {\normalfont\bfseries\centering}
    {}{0pt}{}

• In display format, there is a linebreak between \chaptertitlename \thechapter and the chapter title. Since you don't need Chapter N, I replace display by block.
• The separation between Chapter N and chapter title is set to zero 0pt as well.
• You don't need to use \textbf in \chapter, the chapter title is already in bold (set by \bfseries in \titleformat{\chapter}...).

For detailed syntax and documentation of \titleformat, see titlesec manual, sec. 3.1.

\documentclass[a4paper,12pt,oneside,openany]{book}
\usepackage{tikz}
\usepackage[a4paper, inner=4cm, outer=3cm, top=4cm, bottom=3cm]{geometry}
\usepackage[onehalfspacing]{setspace}
\usepackage{fancyhdr}
\usepackage{titlesec}
\usepackage{setspace}
\usepackage[titles]{tocloft}
\usepackage{tocbibind}
\usepackage{indentfirst}
\fancyhf{}
\cfoot{\thepage}
\linespread{1.5}
\pagestyle{plain}
\renewcommand\cftchapdotsep{\cftdotsep}
\titleformat{\chapter}[block]
    {\normalfont\bfseries\centering}
    {}{0pt}{}

\titlespacing*{\chapter}{0pt}{10pt}{10pt}

\renewcommand{\contentsname}{DAFTAR ISI}
\renewcommand{\listtablename}{DAFTAR TABEL}
\renewcommand{\listfigurename}{DAFTAR GAMBAR}

\addtocontents{toc}{\protect\null\protect\hfill{Halaman}\protect\par}
\setlength\parindent{1.25cm} 
\begin{document}

\frontmatter
\tableofcontents

\pagestyle{fancy}

\mainmatter
\chapter{BAB 1. PENDAHULUAN} 
%TEXT HERE
\section{Latar Belakang}
%TEXT HERE

\end{document}

Update

As requested in comment, to hide the chapter number in \tableofcontents, add following code to preamble, after tocloft is loaded.

\usepackage{xpatch}
% patch the \l@chapter redefined by tocloft package, hide chapter number
\makeatletter
\xpatchcmd\l@chapter
  {\cftchapfont}
  {\let\numberline\@gobble\cftchapfont}
  {}{\fail}
\makeatother