we dont post here for help because we dont know, we know but we ask for other solution other than you used, like a plan b

You might want to rephrase that. Your original post starts with "am having a problem". Indeed, you seem to have to climb a few steps of knowledge before you understand what your script is doing.

I am pretty sure that your script deletes a single user on each button click, so in contrast to your claim you can delete single users. Just compare the content of your database before and after the script ran. Your proposed fix doesn't change that, but doesn't make it worse either, and in any way sending $ENV{SCRIPT_NAME} to the browser has no effect on whether values are stored in a database on the server side.

If you want to make progress, examine the source of the HTML page which your script writes. Then make careful observations which user gets deleted after a click, and then read the documentation of the param method in CGI.

the thing was values run away after page reload,

Which values? Where would you expect them to sit? If you reload a page which came as a response to a POST request, your browser warns you that it needs to resend form data ... and yes, after each such reload, one more user is gone.