How to get rid of Whatsapp?

Just leave and dont use it. None of my friends ever follow me but I dont stop.

Would it help if you told them you think Zuck is creepy? People often have a vague creeped out feeling about Facebook, Meta, and tracking. "I was messaging about (insert) here and started seeing ads for it on all my devices" might sell it and get them on your side.
Beyond that it's the pain point of them installing another app to communicate with likely only you, so leaning on things they already have might work. SMS/MMS may be a viable alternative, or maybe Delta Chat if they'd be willing to share an email address.
It's hard to deal with the saturation levels the big chat apps have so I wouldn't rule out having to keep WhatsApp, unfortunately.

you could also just refuse to use whatsapp and tell your friends to get your alternative if they want to stay in contact with you. if they refuse, their loss.

The only thing that will beat free is convenience.
If you can make it somehow more convenient to use the other alternatives, you may have more luck.
Other than that, you may have to just bite the bullet and stop using it altogether. Be the change you want to see.
We have had good luck with irc, XMPP, and Matrix.

just deinstall it - easy as that

Can't you just make up a story that you got banned from Whatsapp instead of actually trying to get yourself banned?
- no, they will ask for proof, they will be like "ohh that's weird, let me see if I can fix it"
  
  If somebody said that to me, I'd do my best to find a polite way to tell them to fuck off.
  But, since you're situation is, you know, not mine, can you get away with, "Oh, I deleted it, and I'm out of data right now," or some similar kind of deflection?
  
  I can't seem to upload images, but if you image-search for:
  "we've completed our review and found this account's activity goes against whatsapp's terms of service"
  You will find screenshots you can download and use as fake proof that you are banned.
  When I had to contact Facebook to get an account unlocked, they took about a month to respond to each email, and never did unlock the account no matter how much proof I sent them. I expect WhatsApp is similar, since it's owned by the same company. So just say that they hardly respond, and they say things they've already said, ask you to try things you've already tried, or they ask for documents you've already sent them.
  Why were you banned? Maybe you accidentally signed in on a phishing page, and they sent spam using your account. Maybe you created an account, and your first action was to contact a person you hadn't contacted before (obviously), and it was marked as spam. Maybe you signed up on an IP address previously used by a spam-sending datacenter (this happened a lot to me at my old house). Maybe your phone number was banned from WhatsApp before you got it, but you already gave it to too many people to be able to change it.

Install something like GBWhatsapp. Whatsapp seems to do ban waves every now and again so there's no guarantee on the time frame you'll get banned (it took about 4 years for them to catch up with me) but it'll more than likely happen eventually.

Tell your local legislators to make text messages via the regulated phone system work better and cheaper. Back in 2012 I met someone who worked for them (before Meta) and when I said I'd never heard of them he responded "because US phone companies don't rape their customers for text messages". Even today most American's don't use whatsapp because unless you have a message to send international your phone comes with something that works for free.
Whatsapp existing at all is a sign that your phone system doesn't work like it should. This can be fixed.

Get-AppxPackage -AllUsers | ?{$_.Name -like "*WhatsApp*"} | Remove-AppxPackage -AllUsers -ErrorAction SilentlyContinue