You can add or remove the button's shortcode in Customize > Header > Header Text Area:
1. In case you've lost the demo code, you can copy it here:
<a href="/contact/" target="_self" class="vamtam-button accent1 hover-accent2 button-solid" role="button"> <span class="vamtam-button-text">Free Quote</span> </a>
2. You can edit the button link here (the link has to be /inner-page or http://page.com):
<a href="/contact/" target="_self" class="vamtam-button accent1 hover-accent2 button-solid" role="button">
<span class="vamtam-button-text">Free Quote</span>
3. You can also generate some а different shortcode using the Vamtam Beaver Builder (please check Guide to Vamtam Beaver Builder and How to save and re-use particular rows) and add it to the Header Text area.
Next you have to create a Page Builder shortcode (please check https://kb.wpbeaverbuilder.com/article/192-use-shortcodes-in-your-layouts)
Last step is to add the saved row shortcode into the Header text area.