i removed categories URL from product URL now when i access product which is assign to multiple categories generate 404 error but products which assign to only category working fine any help ?
If you have reindexed (catalog url mainly), cleared cache & error persists the most probable is you have something wrong in core_url_rewrite database table
If you have not registered any manual url redirect there you can safely
truncate that table with the database manager you use, as reindex process will fill it back
Be sure to check Magento log files (var/log folder) also, as it is probable reindex process is throwing some errors (duplicate urls or something like that)