This question already has an answer here:
I want to replace '/50' with URL.my URL is
http://localhost/CI/admin/pcustomer/cprofile/50?customer=18267&mobile=&nearby=
I want url as
http://localhost/CI/admin/pcustomer/cprofile?customer=18267&mobile=&nearby=
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From that little info in your question, this seems to be the simplest way to achieve "I want to replace '/50' with URL"
$url = str_replace('/50', '', 'http://localhost/CI/admin/pcustomer/cprofile/50?customer=18267&mobile=&nearby=');