Hi @Pras-495b, welcome to the community, and thanks for posting!
This can be achieved by adding a column in your customer table that stores if the customer is active or inactive (registered or unregistered). With this set up, you can then simply change that status rather than deleting the row of data. This is how it would look:
Here's a Status table:
And a Users table (or Customers, in your case), with a column that is a rowlink to the Status table:
In Builder, you can then create a button with an automation that will update the registration status of a particular user. In my example, I have it look for the row that matches the
$[SYS_USER] (the user currently using the app) and update the status to "Inactive" to unregister the user:
FINDROW formula to update the status:
=FINDROW(Status, "Status[Status]=%", "Inactive")
Now when a user clicks the unregister button, their status changes, but their information remains in the table.
Hope that helps! Let us know if you have any other questions.