Google Spreadsheet Scripting scripting does not add menu and filter does not work as expected

I have the following code, I just write it for practising Google spreadsheet scripting. I have two issues with my code. By the way, it runs and doesn’t throw any errors. However, the issues are a) when I reload/open the spreadsheet it doesn’t load the ‘Custom Formatting’ in the Google Sheet Menu. b) I was expecting that this will check if the filter is ON and if it’s then remove the filter else add the filter. But it adds the filter everytime I run it. This is my very first code in Google Scripting. Please help me find my mistake.

function formatReport() {
  
  let sheet= SpreadsheetApp.getActiveSpreadsheet();

  let headrs = sheet.getRange('A1:F1');
  let table = sheet.getDataRange();
  let filter = sheet.getRange('A1:F1').getFilter();
  if (filter){
    filter.remove;
  }

  else{

  headrs.setFontColor('white');
  headrs.setBackground('#52489C');

  table.setFontFamily('Roboto');
  table.setHorizontalAlignment('center');
  table.setBorder(true,true,true,true,false,true, '#52489C',SpreadsheetApp.BorderStyle.SOLID);

  table.createFilter();
  }


}

function onOpen(){
  let ui =SpreadsheetApp.getUi();
  ui.createMenu('Custom Formatting').addItem('Format Report', formatReport).addToUi;
}

>Solution :

1. addItem‘s second argument is string. You are not calling addToUi()

ui.createMenu('Custom Formatting').addItem('Format Report', 'formatReport').addToUi();

2. You are not calling the remove function

if (filter){filter.remove();}