Hi @PerL
You can remove the sign-in menu by modifying the header web template code.
In portal management:
1. Under Content> Web Templates > Look for Header web template

You have two choices now
1. Find the "Sign_in" liquid HTML blog and remove it. It will be like below
<li role="none">
<a role="menuitem" aria-label="{{ snippets["links/login"] | default:resx["Sign_In"] | escape }}" href="{% if homeurl%}/{{ homeurl }}{% endif %}{{ website.sign_in_url_substitution }}">
{{ snippets["links/login"] | default:resx["Sign_In"] | escape }}
</a>
</li>
2. Or using liquid language add the comments block on the above source code
{% comment %} ....... {% endcomment %}
3. Hit save and close.
In Design studio>
Press Sync configuration > Browse Website
Note: If you already logged in then you need to sign out and try ctrl + F5 or incognito to see the changes
Hope it helps.
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