Students ability to clear history on managed devices

[tneuser]

We currently have our devices set up for students that they cannot clear their browser history. We have just discovered there is a loophole in this setting. If a student signs into their school account on their phone, they can clear their browsing history. Do you know if there is a way to prevent students from signing into a personal device with their school account? Or is there a setting I need to change to prevent students from being able to clear their history on their personal devices?

[kaned]

We also make an effort to block this.

I'm curious to know what the importance to prevent users from clearing history is... 

I am not as concerned about end users doing this because I have a filtering solution in place that logs traffic/history.  This is certainly nice to have for a secondary way to show use/history, but I don't rely on this as a tool or single source of data.

[tneuser]

We also have a filter that logs traffic, but teachers don't have access to it. With the device's history, teachers on site can quickly see what the student has been up to.