The beta profile uploaded on this website is a small configuration file created by Apple itself to help users receive the beta updates they are testing. It includes iOS, iPadOS, macOS, watchOS, tvOS, and HomePod software.
There are 2 types of beta profiles that you need to be aware of: One is the Developer beta profile and the other is the Public beta profile.
Developer profile requires a developer account to download, once installed you will receive beta updates earlier than public beta profile, of course, sooner means less more unstable.
The Public beta profile is released to the public, so you can download it for free from Apple's beta website. Once installed, you can get the same beta updates as when installing the developer profile, but the update time will take longer.
Recently, BetaProfiles.com uploaded public beta profiles, you can choose the type of beta profile you want to download on the homepage.
These profiles are created by Apple. You can check this in "Install Profile" step within the Settings app, make sure the "Signed by" line shows a green "Verified ✓". When you tap "More Detail", you will see Apple certificates.
You should ONLY install this profile when you see these credentials, other websites may fake this to trick you into installing malicious profiles.
Just checking Supported Devices page, I have listed all devices that can install profiles on this site to receive the latest updates.
Unfortunately not, deleting the profile on your device does not revert your device to an earlier software version. This simply stops your device from receiving future developer beta updates.