Deleting records is support in the Advanced Form, Advanced Portal and Advanced Shared View extensions.
Form
To allow users to delete records using the form:
Go to the Share section of your form's settings
Ensure that Allow users to view existing records is turned on
Go to the Security section
Allow users to delete records must be enabled.
Once enabled, the delete button will appear at the bottom of the form.
Portal / Shared View
To allow users to delete records from a portal or shared view:
Go to your extensions Tables list
Select the Child Form for the table you want your users to delete records from (Form for expanding records, if using separate forms for creating and expanding records)
Go to the Security section
Allow users to delete records must be enabled.
Once enabled, the delete button will be available in the three dot menu in the top right corner of the child form.
Optional: Making the delete button show only when certain conditions are met
In addition the steps above:
Create a formula in Airtable with your condition. The formula needs to return 1 when the delete button should be hidden.
Select the newly created field under Hide delete button