How to delete Matrix fields in front end
I've managed to do this with:

&lt;form method="post" accept-charset="UTF-8"&gt;
    {{ csrfInput() }}
    &lt;input type="hidden" name="action" value="users/save-user"&gt;
    &lt;input type="hidden" name="userId" value="{{ currentUser.id }}"&gt;
    {% include '_partial/wish-list-fields' %}

    &lt;input type="hidden" name="fields[userWishListMatrix][{{ block.id }}][type]" value="null"&gt;

    &lt;input type="submit" value="Remove"&gt;
&lt;/form&gt;


The wish-list-fields partial include hidden inputs showing all the fields already there. e.g.:

&lt;input type="hidden" name="fields[userWishListMatrix][{{ block.id }}][fields][itemProperties][0][col1]" value="{{ row.property }}"&gt;


It repeats itself which I know doesn't seem terribly efficient but i dunno :-/ It works!

Please note, I'm on craft3 so things may be a little different (although most likely just the save-user / saveUser action).