Formatting the plugin and removing a payment field

Hello, I’d like to edit the plugin to be larger as I feel it’s too small as of now, and I cannot seem to remove the standard payment options either, all I want is the enter other amount, and the reference text, but not the service – ￡30 option, how should I go about doing this?

Thank you.

https://www.ads-software.com/plugins/wordpress-easy-paypal-payment-or-donation-accept-plugin/