I downloaded the iOS 14 beta now the iOS 14 is out it won’t let me update

Hi, you need to restore your phone as new to remove the iOS 14 Beta & install the official iOS 14 software:

How to uninstall iOS beta software

How to back up your iPhone, iPad, and iPod touch

Restore your iPhone, iPad, or iPod to factory settings

Go to Settings > General > About > Version and tap on it and respond with the build number.

Have you restored your phone to factory settings by connecting it to a computer?

Another way to restore your phone as new, disconnect your phone first from the computer & turn it off: Press and hold the Side button and one of the volume buttons until the power off slider appears. Drag the slider to turn off your iPhone. Then connect your iPhone to your computer while holding the Side button. Keep holding the Side button until you see the recovery mode screen. When you get a message on your computer to update or Restore, select Restore..

Not a good idea to work with betas without a computer. Before you make your appointment remove the beta profile as I suggested above and try the update again.

Do a forced restart of your iPhone then try Settings > General > Software Update again.

You can borrow a laptop from a friend or family member to save you a trip to the Apple store.

Otherwise, you can take your phone to an Apple Store or Apple Authorized Service provider. Book an appointment on getsupport.apple.com or use the Apple Support app.

Make your appointment, they are probably going to need to wipe your iPhone and set up it again. Do an iCloud backup just prior to leaving for your appointment.

same here, i’ve done everything & nothing is working. pls lmk if you found another way!!

What do you mean? You click the "Download and Install" button right there.

Otherwise:

How to uninstall iOS beta software - Apple Support