See this Developer support page. https://developer.mozilla.org/en-US/Firefox/Enterprise_deployment

Beyond that, please see this: https://support.mozilla.org/en-US/kb/where-go-developer-support

how disable this panel she showing at first start and user can get access to settings. Our specialists of security Department want to make sure it was not

English translation?

In English variant (bottom panel and right button on this panel)

I use these pref setting in mozilla.cfg to disable datareporting and telemetry. I don't know if they are all needed for what you want to achieve.

//
lockPref("datareporting.sessions.current.main", 0);
lockPref("datareporting.sessions.currentIndex", 0);
defaultPref("datareporting.healthreport.uploadEnabled", false);
defaultPref("datareporting.policy.dataSubmissionEnabled", false);
defaultPref("datareporting.healthreport.service.enabled", false);
defaultPref("toolkit.telemetry.rejected", true);
defaultPref("toolkit.telemetry.unified", false);
defaultPref("toolkit.telemetry.unifiedIsOptIn", false);
defaultPref("toolkit.telemetry.server", "");

See also Configuration:

• https://developer.mozilla.org/en-US/Firefox/Enterprise_deployment

Thanks! no longer appears.