Remove all trace

I used to use Gsuite (as an admin), and Office 365 ProPlus. I was using a PC, running Windows 7, which auto-upgraded to 10 without permission, a OnePlus 5, iPad mini 4 and a Macbook Air that burnt out. It was terrible. All of it. Still using same iPad and phone number, but I had iCloud and iTunes for PC on the other machine. Honestly, it's too convoluted to give the ridiculous details, so main question: how do I completely disassociate my Apple ID, phone number and e-mail (including conflicting accounts), and my current Apple devices, from Microsoft, Android (especially effing OnePlus), Google and Windows? I do not want aliases using my icloud email address. I do not want separate servers through other services. I do not want remote connections: only straightforward continuity.

I have an iMac 2017 4k, iPad mini 4 A1538, iPhone 8 and AT&T, all 100% up to date, as far as I can tell.