I need an unordered list without any bullets

You can remove bullets by setting the list-style-type to none on the CSS for the parent element (typically a <ul>), for example:

ul {
  list-style-type: none;
}

You might also want to add padding: 0 and margin: 0 to that if you want to remove indentation as well.

See Listutorial for a great walkthrough of list formatting techniques.

If you're using Bootstrap, it has an "unstyled" class:

Remove the default list-style and left padding on list items (immediate children only).

Bootstrap 2:

<ul class="unstyled">
   <li>...</li>
</ul>

http://twitter.github.io/bootstrap/base-css.html#typography

Bootstrap 3, 4, and 5:

<ul class="list-unstyled">
   <li>...</li>
</ul>

Bootstrap 3: http://getbootstrap.com/css/#type-lists

Bootstrap 4: https://getbootstrap.com/docs/4.3/content/typography/#unstyled

Bootstrap 5: https://getbootstrap.com/docs/5.0/content/typography/#unstyled

You need to use list-style: none;

<ul style="list-style: none;">
    <li>...</li>
</ul>

Small refinement to the previous answers: To make longer lines more readable if they spill over to additional screen lines:

ul, li {list-style-type: none;}

li {padding-left: 2em; text-indent: -2em;}

If you're unable to make it work at the <ul> level, you might need to place the list-style-type: none; at the <li> level:

<ul>
    <li style="list-style-type: none;">Item 1</li>
    <li style="list-style-type: none;">Item 2</li>
</ul>

You can create a CSS class to avoid this repetition:

<style>
ul.no-bullets li
{
    list-style-type: none;
}
</style>

<ul class="no-bullets">
    <li>Item 1</li>
    <li>Item 2</li>
</ul>

When necessary, use !important:

<style>
ul.no-bullets li
{
    list-style-type: none !important;
}
</style>

I used list-style on both the ul and the li to remove the bullets. I wanted to replace the bullets with a custom character, in this case a 'dash'. That gives a nicely indented effect that works fine when the text wraps.

ul.dashed-list {
    list-style: none outside none;
}

ul.dashed-list li:before {
    content: "\2014";
    float: left;
    margin: 0 0 0 -27px;
    padding: 0;
}

ul.dashed-list li {
    list-style-type: none;
}

<ul class="dashed-list">
  <li>text</li>
  <li>text</li>
</ul>

If you wanted to accomplish this with pure HTML alone, this solution will work across all major browsers:

Description Lists

Simply using the following HTML:

    <dl>
      <dt>List Item 1</dt>
        <dd>Sub-Item 1.1</dd>
      <dt>List Item 2</dt>
        <dd>Sub-Item 2.1</dd>
        <dd>Sub-Item 2.2</dd>
        <dd>Sub-Item 2.3</dd>
      <dt>List Item 3</dt>
        <dd>Sub-Item 3.1</dd>
    </dl>

Example here: https://jsfiddle.net/zumcmvma/2/

Reference here: https://www.w3schools.com/tags/tag_dl.asp

This orders a list vertically without bullet points. In just one line!

li {
    display: block;
}

To completely remove the ul default style:

    list-style-type: none;

    margin: 0;
    margin-block-start: 0;
    margin-block-end: 0;
    margin-inline-start: 0;
    margin-inline-end: 0;
    padding-inline-start: 0;

If you are developing an existing theme, it's possible that the theme has a custom list style.

So if you can't change the list style using list-style: none; in ul or li tags, first check with !important, because maybe some other line of style is overwriting your style. If !important fixed it, you should find a more specific selector and clear out the !important.

li {
    list-style: none !important;
}

If it's not the case, then check the li:before. If it contains the content, then do:

li:before {
    display: none;
}

You can hide them using ::marker pseudo-element.

1. Transparent ::marker

ul li::marker {
  color: transparent;
}

ul li::marker {
  color: transparent;
}

ul {
  padding-inline-start: 10px; /* Just to reset the browser initial padding */
}

<ul>
  <li> Bullets are bothersome </li>
  <li> I want to remove them. </li>
  <li> Hey! ::marker to the rescue </li>
</ul>

2. ::marker empty content

ul li::marker {
  content: "";
}

ul li::marker {
   content: "";
}

<ul>
  <li> Bullets are bothersome </li>
  <li> I want to remove them </li>
  <li> Hey! ::marker to the rescue </li>
</ul>

It is better when you need to remove bullets from a specific list item.

ul li:nth-child(n)::marker { /* Replace n with the list item's position*/
   content: "";
}

ul li:not(:nth-child(2))::marker {
   content: "";
}

<ul>
  <li> Bullets are bothersome </li>
  <li> But I can live with it using ::marker </li>
  <li> Not again though </li>
</ul>

In BOOTSTRAP You can remove bullets by setting the list-unstyled class on the parent class of the li tag.

<ul className="list-unstyled">
    <li>One</li>
    <li>Two</li>
    <li>Three</li>
</ul>

ul{list-style-type:none;}

Just set the style of unordered list is none.

I tried and observed:

header ul {
   margin: 0;
   padding: 0;
}

 <div class="custom-control custom-checkbox left">
    <ul class="list-unstyled">
        <li>
         <label class="btn btn-secondary text-left" style="width:100%;text-align:left;padding:2px;">
           <input type="checkbox" style="zoom:1.7;vertical-align:bottom;" asp-for="@Model[i].IsChecked" class="custom-control-input" /> @Model[i].Title
         </label>
        </li>
     </ul>
</div>

In case you want to keep things simple without resorting to CSS, I just put a   in my code lines. I.e., <table></table>.

Yeah, it leaves a few spaces, but that's not a bad thing.