find the below code in your theme.
<tr>
{% for column in table.columns %}
<td style="font-weight: bold; padding: 5px 10px; text-align: {{ column.align }}; border-left-width: 1px; border-bottom-width: 1px; border-top-width: 1px{% if forloop.last == true %}; border-right-width: 1px{% endif %}{% if column.nowrap %}; white-space: nowrap; width: 80px{% endif %}">{{ column.label }}</td>
{% endfor %}
</tr>
replace the above with the following code.
<tr>
{% for column in table.columns %}
{% if column.label != 'HSN' %}
<td style="font-weight: bold; padding: 5px 10px; text-align: {{ column.align }}; border-left-width: 1px; border-bottom-width: 1px; border-top-width: 1px{% if forloop.last == true %}; border-right-width: 1px{% endif %}{% if column.nowrap %}; white-space: nowrap; width: 80px{% endif %}">{{ column.label }}</td>
{% else %}
<td style="font-weight: bold; padding: 5px 10px; text-align: {{ column.align }}; border-left-width: 1px; border-bottom-width: 1px; border-top-width: 1px{% if forloop.last == true %}; border-right-width: 1px; white-space: wrap; width: 80px">{{ column.label }}</td>
{% endif %}
{% endfor %}</tr>
Adjust the width after the {% else %} tag according to your size requirements.