In Order to exiting products urls from system

1. First Take backup of core_url_rewrite table.
2. Then you need to running mysql delete query at core_url_rewrite which will delete.

Sql1:

Delete FROM core_url_rewrite WHERE product_id is not null

Sql2:

Delete FROM core_url_rewrite WHERE category_id is not null

3.delete All exiting url_keys from catalog_product_entity_varchar table.

DELETe FROM catalog_product_entity_varchar where attribute_id =(SELECT attribute_id FROM eav_attribute WHERE attribute_code LIKE 'url_key' and entity_type_id=4 )

4. Then re-index Catalog URL Rewrites from Index Management

In Order to remove exiting products urls from system.You need to follow below steps:

1. First Take backup of core_url_rewrite table.
2. Then you need to running some mysql delete queries at core_url_rewrite which will delete.

Sql1:

Delete FROM core_url_rewrite WHERE product_id is not null

Sql2:

Delete FROM core_url_rewrite WHERE category_id is not null

3.delete All exiting url_keys from catalog_product_entity_varchar table.

DELETe FROM catalog_product_entity_varchar where attribute_id =(SELECT attribute_id FROM eav_attribute WHERE attribute_code LIKE 'url_key' and entity_type_id=4 )

4. Then re-index Catalog URL Rewrites from Index Management

In Order to exiting products urls from system

1. First Take backup of core_url_rewrite table.
2. Then you need to running mysql delete query at core_url_rewrite which will delete.

Sql1:

Delete FROM core_url_rewrite WHERE product_id is not null

Sql2:

Delete FROM core_url_rewrite WHERE category_id is not null

3. Then re-index Catalog URL Rewrites from Index Management

In Order to exiting products urls from system

1. First Take backup of core_url_rewrite table.
2. Then you need to running mysql delete query at core_url_rewrite which will delete.

Sql1:

Delete FROM core_url_rewrite WHERE product_id is not null

Sql2:

Delete FROM core_url_rewrite WHERE category_id is not null

3.delete All exiting url_keys from catalog_product_entity_varchar table.

DELETe FROM catalog_product_entity_varchar where attribute_id =(SELECT attribute_id FROM eav_attribute WHERE attribute_code LIKE 'url_key' and entity_type_id=4 )

4. Then re-index Catalog URL Rewrites from Index Management