If you want to offer users the ability to delete records in your application, but don't want them to be actually permanently deleted, you can implement a "soft deletion" feature (kind of like dragging files to the trash, but not emptying it yet).
To implement this, add a Yes/No field to the object called something like "Deleted?" and make the default value "No". (If you have existing records, you may want to use Knack Batch Update feature to mark all of them as "No".)
Then, when you build your tables or lists to show your records, instead of using the Knack feature to insert a Delete link (which would permanently delete the record), add an Edit form in a modal window. Remove all the fields that Knack adds to the form by default - this is really just a message window, but the purpose is to use the Record Rules (see below). You could add a Title field to say something like "Are you sure you want to delete?". You could also include some identifying fields on this form, such as the name of the record - you can set these to "Display the field value without a form input" so they don't show as editable:
On this "Edit" form, go to Form Rules / Record Rules. Create a rule to set the "Deleted?" field to "Yes", like this:
Finally, in your tables and lists showing these records, go to the Data Source page, and in the Data section, add a rule to show only records where "Deleted?" is "No".
Now, users will have a normal experience of deleting a record and it will no longer show up for them. But, the records still exist in the database. You could provide a "Trash Can" type of interface for users to "un-delete" these records, or you could make that option available only to admins.