Re: How to list tags on forum.php
topic_tags() will invoke the topic-tags.php file in your template (or if that file doesn’t exist in your template, in the default template).
At the bottom of the code in that template, there is a tag_form(); invocation. To not have the form appear, you could try invoking the rest of the code on that page (without that tag_form invocation).
The “delete tag” link will appear as long as you are logged in as an admin. It won’t appear to most users when you’re not logged in. So you shouldn’t worry about that appearing.