How do I get spyware off of my iPhone?

Hey there,

iPhone cannot be infected with viruses / Malware / Spyware if it is updated to the latest iOS unless you have intentionally downloaded spurious software or unauthorized apps directly from the internet and installed on your device or/and have Jail Broken. 

Why do you think there is spyware on your iPhone ?

erase website data and history, in Settings, Safari

The only way that spyware can be on your phone is if you installed it from the App Store, assuming you didn't jailbreak the phone

So uninstall it in the usual way.

There is no way that hidden spyware can be on your phone since Pegasus was neutralised.

search marquis.com has become my start page, and I can't change it.