delete URLs of all terms for a specific taxonomy vocabulary
To delete the aliases you will need a custom module or perhaps a custom VBO action based on the update taxonomy term alias action.  Here is a quick and dirty version of a custom module

aliases_delete.info

name = delete aliases
description = will delete vocabulary aliases for specific vocabulary 
package = aliases_delete
version = 1
core = 7.x
dependencies[] = pathauto


aliases_delete.module

&lt;?php

function aliases_delete_menu() {
  $items['aliases_delete/%'] = array(
    'page callback' =&gt; 'aliases_delete_delete_vocabulary',
    'page arguments' =&gt; array(1),
    'access callback' =&gt; 'taxonomy_term_edit_access',
    'access arguments' =&gt; array(2),
  );
  return $items;
}

function aliases_delete_delete_vocabulary($vocabulary_name){
  $vocab = taxonomy_vocabulary_machine_name_load($vocabulary_name);
  $terms = entity_load('taxonomy_term', FALSE, array('vid' =&gt; $vocab-&gt;vid));
  foreach ($terms as $term) {
    pathauto_entity_path_delete_all('taxonomy_term', $term, "taxonomy/term/{$term-&gt;tid}");
  }  
  return 'Deleted aliases of all terms in ' . $vocabulary_name;
}


If you enable and install this module you can visit as admin aliases_delete/tags to delete all aliases of terms in vocabulary tags

To update the path aliases of specific taxonomy terms (instead of deleting) you can use VBO - views_bulk_operations


install and enable the module
create a view of taxonomy terms and use appropriate filters for vocabulary
add field "view bulk operations" and save your view
go to your view and select all terms that will be updated (VBO can select multiple pages of results)
choose the update taxonomy term alias action and press execute 
all terms should be updated according to the new pathauto rules