The person can either do it right now and they do not have to wait, or the person cannot do it at all and it may that the threat to remove it is part of the scam and they can't really. If the person has your account information and your phone as a trusted device then there is little you can do at this stage. Unfortunately you provided the information they needed to get full access to everything to do with your account and equipment.
Read this document if you think your Apple ID has been compromised. --> If you think your Apple ID has been compromised - Apple Support
For iOS 15 or earlier, if you want to see if anyone else has access to your device or accounts, click here --> Limit access to your iPhone or iPad - Apple Support
For iOS 16 or later see how Safety Check on iPhone works to keep you safe. How Safety Check on iPhone works to keep you safe - Apple Support
Use the information in this document to check your Apple ID device list to find where you're signed in --> Check your Apple ID device list to find where you're signed in - Apple Support
Related materials:
Personal Safety User Guide
Personal Safety User Guide - Apple Support
> open the Table of Contents and review the articles
A document with general information about security and your Apple ID --> Security and your Apple ID - Apple Support
Contact Apple for help with Apple ID account security. This page provides country-specific Apple Support contact information ➞ Contact Apple for support and service - Apple Support
