If you have lot of categories in your wordpress blog and looking to merge the categorize, there is unfortunately no straight forward plugin for it which is indeed very surprising. Still there is one wordpress plugin which works well to merge wordpress categories which is merge tags

It is intended to be used for tags merging but works really well with categories too, just download and install the plugin, activate it and go to this url (insert your blog url in front of it)

/wp-admin/edit-tags.php?taxonomy=category

you can add which category you want to merge with which category.

There are couple of other methods too but they are manual.

Lets say you have a category Nike and Adidas and you want to merge them into a Category Shoes, so under categories /wp-admin/categories.php make Shoes as the default category and delete both Nike and Adidas category, be default, if you delete any category, all the posts under that category comes to Default category i.e. in our case, in Shoes.

If you know any other way of merging wordpress categories, please post them in comments.

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