How can I make an Android app "forget" that it installed on my phone before? Some apps, like Facebook, LinkedIn, Tinder, etc., seem to have a mechanism to remember which Android phone installed their app. So if a user is banned on these apps, the next time somebody creates an account on the same Android phone, that account is flagged or even banned automatically.
What is the way to make sure the app forgets that my Android phone was used previously with a banned account? I tried to clear the cache and delete app data, then uninstall the re-install the app, but it still remembers! I tried it on different IP addresses, but the same issue is there.
Does the app have access to the IMEI of the phone!??
I am on Android v10.
tl:dr; addressing OP's question - sorry, no way AFAIK. From Android 10 onwards normal apps can't access IMEI number.
Revised answer with additional inputs from Izzy (thanks)
How do apps (Google or third party) identify you?
Apps identify a device using:

Some or all of device identifiers, mainly Android ID, GSF Android ID, build serial number, and advertising ID. I know of one paid app which tracks IMEI too (before Android 10). It depends on the developer as to how badly they want to identify you and prevent installation of apps. See this excellent write up by Izzy (a moderator here) for more details Android Identifiers: How Android devices and their users are identified. It is rare that an app depends only on one type of identification. I have observed over the last three years that shopping , banking, social media &amp; social media related apps are particularly nasty and use every trick in the book.

In addition to this apps come packaged with trackers and loggers (all utilities which are used to log user activity on an app or logcat in general), which identify the user and their browsing patterns , in addition to fingerprinting user by device identification. These can be used for benign purposes in theory but in practice can extend to key logging features that can track what you type. Have a look at Staggering variety of clandestine trackers found in popular Android apps.


What happens to this data?
Those identifiers are stored on third-party servers (analytics companies and other &quot;big data collectors&quot; such as Facebook, Google, Amazon, Microsoft, etc.) – so once collected, there's no chance you can delete that. Some offer an opportunity to sign out, but there is no way you can have that data deleted. Even if it is legally possible under GDPR (which I doubt), it is not a trivial task to get this implemented across hundreds of trackers/loggers.
How can I prevent from being tracked/ identified?
Root is a must for full control over this menace (see rooting) That's the unfortunate part. Without root you can only choose apps with care and probably try some hacks which in the long run aren't effective or at best partially useful.

Choose the apps you want to install with care: Up to a degree, apps like TrackerControl or Warden can help. Ideally, you avoid apps including trackers; Exodus Privacy is a good helper for that – and Izzy's app listings use such services to &quot;mark&quot; apps, making it easier for you to sort the wheat from the chaff.

Feed them faked information: This approach is better than denying permissions because it doesn't result in malfunctioning apps or apps that crash. Highly recommend you to use XPrivacyLua being the most effective broad spectrum measure. This requires EdXposed to be installed from Android 8 and above (see the restrictions section to see what can be faked). If you are on earlier versions Xprivacy by the same developer does the job with Xposed. Even XPrivacyLua can't help in instances when the app code is obfuscated.
The Warden app mentioned above can also &quot;nuke&quot; your device, making it free
from trackers and loggers. It also gives you flexibility to tackle apps on individual basis. The Warden App Manager uses a static list of trackers and loggers compiled by French non-profit Exodus Privacy.


While Android has been showing greater concern for privacy and PII information over the last few versions, this problem is not significantly mitigated even in Android 11 (no prizes for guessing why. Google is probably the biggest data aggregator).