Hi,
Pass  partner_category_display == short in the field context or action context, then it will show only the exact name instead of parent/name.
Sample: context="{'partner_category_display': 'short' }"
See the name get function:
def name_get(self):
    """ Return the categories' display name, including their direct
        parent by default.
        If ``context['partner_category_display']`` is ``'short'``, the short
        version of the category name (without the direct parent) is used.
        The default is the long version.
    """
    if self._context.get('partner_category_display') == 'short':
        return super(PartnerCategory, self).name_get()
    res = []
    for category in self:
        names = []
        current = category
        while current:
            names.append(current.name)
            current = current.parent_id
        res.append((category.id, ' / '.join(reversed(names))))
    return res
Thanks