Nginx And Apache web server conflict on ubuntu server [closed]

I'm running a Java (Spring Boot) application along with an Angular front-end on an ubuntu VPS. I'm using Nginx as a reverse proxy to route requests to Java (port 8080) and Angular files. After Installing cPanel and WHM on the server (to manage domain and Email stuff) I realized that both run on port 80 and Nginx shuts down randomly! First I tried to kill all the processes of apache (httpd) by sudo kill -9 [httpd process ids]. But after some time httpd comes again and steals port 80 so nginx service is being terminated! What should I do for solving this problem?