Disable Shipping Method After Specified Dollar Amount Is Reached

I have 2 shipping methods available. One is ups or fedex ground (signature not required) and the second is ups or fedex ground (signature required) in which I get an extra dollar amount. I am using manual setting. Once the order reaches $500 usd, I only want to offer the "Signature Required".

So, I would like to disable a particular shipping method when the order amount reaches $500.

By doing this, I will be able to offer only one shipping method that requires a signature.

Any ideas?

For example, you can use shippings_calculate_rates_post hook in the app/Tygh/Shippings/Shippings.php file to change calculated rates for specific shipping method and service