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>