You should already know how big tech companies like Google or Facebook are using your private data to make revenue from targeted ads (and sometimes maybe sell it under the hood without your knowledge). There is no secret about data being the most valuable asset on earth now - even exceeding the oil.
Some people say "I have nothing to hide, I don't care" which is essentialy ignoring basic human right and making this right worthless to you and very precious to others. We are already living in Cyberpunk era and the world is starting to be led by big organizations rather than governments so let's try to prepare ourselves and start to care about our data.
I think Google and Facebook are particulary bad when it comes to the data - we all heard about Cambridge Analytica and lately about Whatsapp scandal. Removing Facebook account is slightly easier than moving away from your Google account. It's impossible to just toggle some settings and let go your gmail address, google search, photos, youtube - pretty much your entire digital life.
Recently Google changed their policy for storing photos. Starting from July 2021 you won't have unlimited High Quality storage as before rather than 15GB limit. This is still okay in terms of space but the politics behind it is just disgusting. Google was effectively feeding it's photo AI algorithms for face detection and tagging for years now using user data obtained by giving up the service for free. Now when these algorithms got so good and it's almost impossible to make them better and Google don't need users anymore they switched to make some money from the service.
Backup with Google Takeout
To download and backup all your data it's best to use Google Takeout.
Follow the intructions and soon you'll get an email with links to your data. After you safely obtain it, start clearing your Google account.
Clear your account
To remove all photos and videos you need to go to photos.google.com and remove them from there. This might not be as quick as clicking a button.
Youtube, Gmail, Google One
Go to Delete services or account page and choose what services to remove.
Google Meet & Calendar
Hard one. People often invite you for online meetings using both services. You can't force them to not use those but you can always use private browser mode.
Hardest one. Google's core product and definetely the best one on the market. You can switch to Duck Duck Go which is okay and does the job.
I know it's really hard to remove Youtube and Gmail for example. There is no other place than Youtube where all my favourite creators are and many people already have my Gmail address and contacting me via this one. What I did is setup an email forwarding (yes I know Google can still track messages) and start using Youtube only via iOS App to avoid auto-logging in browser.
If you are really hardcore about this you can always go and Delete account completely 🤫