Activate/Deactivate allow_url_fopen Print

You can change this parameter through users PHP selector :
cpanel>>select php version>>switch to php options.  

Also you can enable it using console. For example for version 7.1 and user testuser:

selectorctl --replace-options=allow_url_fopen:on --version=7.1 -u testuser

then you can check: 

selectorctl --print-options --version=7.1 -u testuser| head -n5

More about selectorctl command you can find here:
https://docs.cloudlinux.com/selectorctl.html