Hello GraceArifuku,
I'm Jin, a fellow Windows 10 user and an independent advisor. I can see that you have some concern with using Edge on your iPhone.
The lock with the blue shield icon indicates that the website is secure. It's an indicator that the website is safe. It's not something you can remove and you will find that helpful when surfing the web.
As for Microsoft Rewards points, you can review this article:
https://support.microsoft.com/en-us/help/20540/...
I hope this would help you.