Fix PHP bug in betting software

We have a PHP/MySQL sports betting software (not made using any framework, but plain PHP) , which in a specific part have part, after user have logged in, user may see and edit some scores of match games, the match games have: DATE -TIME - TEAM 1 NAME - TEAM 2 NAME and for each one of the 2 teams , user may select the score (from 1 to 20). After the DATE - TIME users are not able to change the scores. The form where user input their scores, uses a <form action=" "> line to call another PHP script and save the scores in the database. But we are facing a problem and is that some users are saving the generated HTML in their computers or using the INSPECT ELEMENT option of their browsers, and are able to delete HTML code disabled="disabled" , run the html in their computers , change score of matches that have already finished and save their data in the server database cheating the system. This is a sample line where they can remove the disabled="disabled" and save the data from their computers: <select name="team_1_score1_" id="team_1_score_49" class="XXXXXX" disabled="disabled"> So we help in modifying this PHP script so users can not change their scores after the DATE -TIME of the matches from HTML that they save and change in their computers or by using the INSPECT ELEMENT option of their browser. We will provide access to CPANEL where this software is located, and will give you a video replicating the current bug that needs to be fixed. Thanks!