The message Roblox sent me:
[Important] GDPR Right to Erasure - Action Requested ROBLOX Oct 31, 2019 | 9:38 PM Hi Dev,
We received a right-of-erasure-request for the following User ID: [some number]. Please delete this User ID immediately from all of your records (e.g. games, data stores, etc.), as this is an obligation under European Data Protection Laws. If you would like more information about how to delete a User ID from a data store, please visit our Developer Hub at https://developer.roblox.com/articles/Data-store and https://developer.roblox.com/api-reference/class/GlobalDataStore.
Please note that you must delete the User ID from all of your records, and not just from your data stores. The pages linked above are provided for informational purposes and are not intended to provide a comprehensive method of deleting User IDs.
Regards, The Roblox Team
The way I store player data in my games:
the first game
local DataStoreService = game:GetService('DataStoreService')
local playerData = DataStoreService:GetDataStore('Stage')
playerData:SetAsync(Player.UserId, **a check point name**)
the second game
local playerData = DataStoreService:GetDataStore('Money')
local playerData2 = DataStoreService:GetDataStore('Launcher')
playerData2:SetAsync(player.UserId, **the name of a launcher**)
playerData:SetAsync(player.UserId, **some points value**)
My question is then how I should code to avoid these right of erasure requests. (I have deleted the player from my data stores btw.)

3 comments
So am I suppose to ignore these requests or what is the solution?
NO. Do not ignore them, you have to delete the player's data.
You do what the error says. Also, you really should avoid waiting 4 months when you need to do something from a legal request. Also, this is off-topic.