How to delete a number that does not fall into contacts?

Question

Android

Hello.
I am writing a hidden messenger (I also doubt the expediency =)) I launch it by means of a password call, that is, the user calls, for example, number ###123 and the messenger starts, after which I want to remove this number from outgoing. The problem is that this number is displayed in the standard dialer but is not displayed in contacts
Checked everything by uri just in case

Cursor cursor = getContentResolver().query(ContactsContract.Contacts.CONTENT_URI, null, null, null, null);

alas, it is not there, perhaps due to the fact that the number is not valid, it does not get into contacts, but then where and how to look for it?